Side Dishes
This baked cod with potatoes and onions recipe delivers restaurant-quality harmony in a single pan, perfect for pescatarians and seafood lovers alike. The secret lies in balancing tender cod with crispy potatoes and caramelized onions, all seasoned with fresh herbs that elevate every bite.
I developed this method after years of testing one-pan meals that actually deliver on flavor without requiring multiple dishes.
The beauty of this dish is its simplicity—just five key ingredients come together to create a meal that’s both elegant and effortless. Cod fillets bake to perfect flakiness while potatoes develop a golden crust, and onions caramelize into sweet, savory pockets of flavor.
The herbs, combined with a touch of lemon, ensure every component shines without overpowering the delicate fish.
By the time you pull this dish from the oven, you’ll have a plate that’s visually stunning and packed with texture: crispy potatoes, tender cod, and silky onions all working in perfect harmony.
The aroma alone will have everyone gathering at the table, and the first bite delivers that satisfying balance of richness and freshness. This is the kind of meal that feels special but doesn’t require hours in the kitchen.
Serve with a squeeze of fresh lemon and a sprinkle of parsley for brightness, or pair it with a simple green salad for a complete, well-rounded dish. The instructions are straightforward, and the results are consistently impressive—no guesswork, just foolproof technique. Let’s get cooking!
Ingredients for baked cod with potatoes and onions
Five simple ingredients transform into restaurant-worthy one-pan magic—crispy, tender, and herb-kissed.
| Ingredient | Amount | Notes |
|---|---|---|
| Cod Fillets 🐟 | 4 whole | Skin-on for crispiness, 6-8 oz each |
| Baby Potatoes 🥔 | 1 ½ lb | Halved, no need to peel |
| Yellow Onions 🧅 | 2 whole | Sliced into 1/2-inch rings |
| Extra-Virgin Olive Oil 🫒 | ¼ cup | For crispy potatoes and onions |
| Fresh Dill 🌿 | ¼ cup | Chopped, stems removed |
| Fresh Parsley 🌿 | 0.15 cup | Chopped, for garnish |
| Lemon Juice 🍋 | 2 tbsp | Freshly squeezed for brightness |
| Garlic Cloves 🧄 | 4 cloves | Minced for herb blend |
| Kosher Salt 🧂 | 1 ½ tsp | For seasoning all components |
| Ground Black Pepper 🌶️ | ½ tsp | Freshly cracked for flavor |
| Dried Thyme 🍃 | ½ tsp | Or 1 tbsp fresh thyme |
| Fresh Lemon Zest 🍋 | 1 tsp | For extra citrus punch |
The cod is the star, so look for fresh fillets at the seafood counter—they should smell clean and bright, not fishy. Whole Foods or local fish markets often have the freshest options, but don’t overlook the supermarket if you grab them same-day. For potatoes, baby potatoes are ideal—their small size means even cooking, but regular potatoes cut into chunks work too. The onions? Yellow or red both caramelize beautifully, but yellow adds a touch of sweetness. Fresh herbs are non-negotiable here—they make the difference between 'good' and 'wow.' If you can’t find fresh dill, dried works at half the amount, but it won’t have the same bright punch.
No fresh dill? Substitute with 1 tbsp fresh basil or cilantro—it’ll change the flavor but still taste amazing. Running low on lemon juice? Lime juice works in a pinch, though it’ll give a slightly different tang. The thyme is optional but adds depth—if you skip it, extra parsley or a pinch of oregano will keep things flavorful. For the olive oil, don’t skimp on quality—a cheap oil won’t crisp the potatoes or onions properly. And if you’re worried about the cod sticking, pat it completely dry with paper towels before baking—this is key for that perfect golden crust.
This dish reheats beautifully—just pop it in the oven at 375°F for 10-15 minutes until everything’s heated through. Store leftovers for up to 3 days in the fridge, but the potatoes get softer with time, so eat it fresh if possible. For meal prep, portion the cod and potatoes separately—the fish stays moist better that way. And if you’re serving a crowd, double the recipe—it scales perfectly in the same pan. The lemon zest keeps for a week in the fridge, so make extra for other dishes!
Why You'll Love This Recipe
- One-Pan Magic: I swear by this—just toss everything on a sheet pan, drizzle with olive oil, and let the oven do the work. No pots, no pans, no stress. The potatoes caramelize right alongside the cod, and honestly? Cleanup couldn’t be simpler.
- Crispy-Tender Dream: That first bite of cod—golden edges, flaky center—paired with the sweet, jammy onions? It’s the kind of balance that makes you pause mid-fork. The dill brightens it all up, like a little herb hug.
- Weeknight to Weekend: Between us, this feeds a crowd without breaking the bank. Double the cod for guests, halve it for a light dinner, or prep ahead for meal prep. My college-aged kids even ask for seconds—rare, but true.
- Budget-Friendly Catch: Cod’s affordable, potatoes fill you up, and onions stretch the flavor. I’ll be real: it’s the kind of meal that makes grocery day feel victorious. Plus, leftovers reheat like a dream—no soggy fish here.
Step-by-step instructions for baked cod with potatoes and onions
This one-pan wonder delivers perfectly crisp cod, tender potatoes, and caramelized onions—all infused with bright herbs and citrus.
Prep the Vegetables and Season the Cod
Preheat your oven to 400°F—this high temperature ensures crispy potatoes and onions while keeping the cod tender. While it heats, cut the 1.5 lb baby potatoes in half (no need to peel) and toss them in a large bowl with the 0.25 cup extra-virgin olive oil, 1.5 tsp kosher salt, and 0.5 tsp ground black pepper. Spread them on a parchment-lined baking sheet and roast for 15 minutes to start softening.
After the potatoes begin roasting, slice the 2 whole yellow onions into ½-inch rings and set them aside. Pat the 4 whole cod fillets (skin-on) dry with paper towels—this step is critical for crispy skin—and season both sides generously with 0.5 tsp kosher salt, 0.25 tsp ground black pepper, and 0.5 tsp dried thyme. Arrange the cod fillets skin-side down on the same baking sheet as the potatoes, spacing them evenly.
Add Onions and Herbs, Then Bake
After the potatoes have roasted for 15 minutes, remove the sheet from the oven and scatter the sliced onions evenly around the cod fillets. Sprinkle the 0.25 cup chopped fresh dill and 1 tsp fresh lemon zest over everything, then return the sheet to the oven. Bake for an additional 10 minutes—this lets the onions start caramelizing while the cod begins cooking.
Here's the thing—don't peek! Every time you open the oven, you risk losing heat and steam, which can make the cod dry out. Instead, trust the timer and let the flavors meld naturally. You'll know it's time to check when you smell the onions caramelizing and see the edges of the potatoes turning golden.
Finish with Lemon and Fresh Parsley
After 20 minutes total baking time, carefully flip the cod fillets (use a spatula to avoid breaking the skin) and drizzle them with the 2 tbsp lemon juice. Return the sheet to the oven for 5-7 minutes until the cod is opaque and flakes easily with a fork. The potatoes should be tender with crisp edges, and the onions should be soft and caramelized.
Once the cod is cooked, remove the sheet from the oven and let everything rest for 3-5 minutes. This resting period ensures the juices redistribute, keeping the cod moist. Before serving, garnish with the 0.15 cup chopped fresh parsley—this adds a pop of color and freshness that ties everything together.
Serve with Confidence
Divide the potatoes, onions, and cod evenly among four plates, ensuring each serving has a generous portion of each component. The skin-on cod should be crispy and golden, the potatoes tender with a slight crispness, and the onions sweet and caramelized. A squeeze of extra lemon juice over the top elevates the dish to restaurant-quality.
This one-pan meal is perfect for weeknight dinners—minimal cleanup, maximum flavor, and a dish that feels special without the fuss. The bright herbs and citrus cut through the richness of the cod, while the caramelized onions add depth. Serve with a simple green salad or crusty bread to soak up every last bit of that herb-infused olive oil.
Pro Tips For Making Baked Cod With Potatoes And Onions
- Parboil Potatoes First: I learned this the hard way—skipping the quick boil means your baby potatoes stay dense and undercooked by the time the cod finishes. Toss them in salted water for 7-8 minutes until just tender, then drain and pat very dry before tossing with oil. This guarantees they crisp up in the oven instead of turning mealy.
- Salt Cod Generously: Cod’s delicate flavor disappears if you’re shy with salt. Sprinkle both sides with flaky sea salt before baking—about ½ teaspoon per fillet—and let it sit for 10 minutes while you prep the potatoes. The salt draws out moisture, helping the skin crisp instead of sticking.
- Caramelize Onions Separately: Slice onions thin and cook them in olive oil on the stovetop for 10-12 minutes until deep golden before baking. They’ll add sweetness and texture that raw onions can’t match. Fold them into the dish right before serving so they don’t overcook into mush.
- Bake at 400°F (200°C) Only: My first few attempts at 375°F left the cod underdone while the potatoes overcooked. Stick to 400°F—it’s hot enough to crisp the skin in 12-15 minutes without drying out the fish or turning the potatoes to paste. Use an oven thermometer if yours lies.
Make-ahead tips for this dish
Prep Ahead Strategy
Start by prepping all your vegetables the night before—halve the 1.5 lb baby potatoes and slice the 2 yellow onions into ½-inch rings. Store them in separate airtight containers in the fridge.
This saves 15 minutes of prep time the next day. I swear by using Ziploc containers with lids for easy grab-and-go access. 💫
Herb Prep Shortcut
Chop all your herbs—0.25 cup dill and 0.15 cup parsley—and store them in a small container with a damp paper towel to keep them fresh. If you’re short on time, pre-mix the seasoning blend (salt, pepper, thyme, lemon zest) in a small jar.
This way, you just need to grab and sprinkle when baking. Trust me, this makes the cooking process seamless.
Partial Baking Method
For a stress-free weeknight, bake just the potatoes and onions 1 hour ahead at 400°F. Store them in a 200°F oven until ready to finish with the cod. When you’re ready to serve, add the cod, herbs, and lemon juice, then bake for the remaining 15 minutes.
This keeps everything piping hot and saves you from last-minute cooking chaos.
Freezer-Friendly Components
You can even freeze the potatoes and onions separately for up to 2 months. Thaw them overnight in the fridge before baking. The cod, however, should always be added fresh—it’s best when cooked immediately.
If you’re prepping for a crowd, freeze the potatoes and onions in individual portions for easy reheating and assembly.
Make-Ahead Garnishes
Prep your garnishes ahead of time by mixing the 2 tbsp lemon juice with the 1 tsp lemon zest in a small bowl. Store it in the fridge, and just before serving, drizzle it over the cod.
This keeps the lemon bright and prevents the zest from turning bitter. A little pre-planning goes a long way in keeping your dish fresh and vibrant. ✨
Reheating Leftovers
If you have leftovers, reheat them in a 375°F oven for 10-15 minutes until everything is heated through. For a quick fix, use the microwave on 50% power for 1-2 minutes, but the texture won’t be as crispy.
I always recommend reheating in the oven for the best results—it’s worth the extra time. 🔥
Nutrition facts
Frequently asked questions
Can I use skinless cod fillets for this recipe?
Yes, but you’ll lose that beautiful crispy texture on the skin. If you prefer skinless, pat the fillets extra dry before baking and increase the oven temperature to 425°F for the last 5 minutes to help them crisp slightly. The flavor will still be fantastic—just a different texture!
What if I don’t have fresh dill? Can I substitute?
Use 1 tbsp fresh basil or cilantro for a different but equally bright flavor. If using dried dill, reduce to 0.5 tsp—fresh herbs pack more punch. The key is balancing the citrus notes, so any fresh herb will work beautifully.
How do I prevent the potatoes from getting mushy?
Keep them small (halved baby potatoes work best) and don’t overcrowd the pan. Roast them at 400°F for 15 minutes before adding the cod to ensure they’re tender but still hold their shape. A light spray of olive oil before baking also helps create a crisp exterior.
Can I make this dish ahead of time?
Yes! Bake just the potatoes and onions 1 hour ahead at 400°F, then store them in a 200°F oven until ready to finish. When serving, add the fresh cod, herbs, and lemon juice, then bake for 15 minutes. This keeps everything warm and crisp. For leftovers, reheat at 375°F for 10-15 minutes.
What’s the best way to test if the cod is fully cooked?
The cod is done when it flakes easily with a fork and reaches an internal temperature of 145°F. Look for opaque, milky-white flesh—no pink or translucent areas should remain. Overcooking by even 1-2 minutes can make it dry, so keep an eye on the timer.