Why this recipe works

Temperature precision. Baking at 400°F creates the ideal environment for white fish—hot enough to develop a light crust and cook through quickly, but not so hot that the exterior overcooks before the center is done. This temperature allows the fish proteins to coagulate gently rather than seizing tightly, resulting in the characteristic large, moist flakes of properly cooked white fish.

Marinade chemistry. The olive oil and lemon juice marinade serves multiple purposes: the oil carries fat-soluble flavors from the herbs and garlic into the fish, while the acid in the lemon juice gently denatures surface proteins, allowing the seasonings to penetrate slightly. The balance is crucial—too much acid and the fish becomes ceviche-like; too little and the flavors remain superficial.

Moisture management. Patting the fish dry before applying the marinade is non-negotiable. Surface moisture steams rather than bakes the fish, preventing proper browning and creating a watery texture. The oil in the marinade then creates a barrier that helps retain the fish’s natural moisture during cooking.

Flavor contrast engineering. The olive salsa provides three essential contrasts: briny (olives, capers), acidic (lemon juice), and fresh (herbs, tomatoes). This combination cuts through the richness of the baked fish without overwhelming its delicate flavor. The salsa’s texture contrast—chopped but not puréed—adds interest without competing with the fish’s flakiness.

Timing synchronization. The fish bakes in the time it takes to prepare the salsa, making this an efficient weeknight meal. The salsa ingredients benefit from 10-15 minutes of marinating time anyway, allowing flavors to meld while the fish cooks. This parallel preparation ensures both components reach their peak at the same moment.

Ingredients (cups & tablespoons only)

Nutrition (estimated)

Nutrition calculated with cod fillets and standard ingredient measurements. Values are estimates and will vary based on specific fish type and olive brands used.

Fish selection & preparation

Baking science & temperature control

White fish contains delicate proteins that coagulate at relatively low temperatures (around 140-145°F). The 400°F oven temperature creates the ideal environment for gentle, even cooking without excessive moisture loss.

Protein coagulation stages

• 120-130°F: Proteins begin to denature, flesh becomes opaque
• 140-145°F: Optimal doneness—proteins fully coagulated but still moist
• 150°F+: Overcooked—proteins tighten excessively, squeezing out moisture
• 160°F+: Dry, tough, rubbery texture

The visual cue of “flaking easily” occurs around 145°F internal temperature. Using an instant-read thermometer provides the most accurate results, especially when working with unfamiliar fish types or thicknesses.

Salsa balance & flavor development

The olive salsa serves as both garnish and sauce, providing multiple flavor dimensions that complement the simple baked fish. Each ingredient contributes specific characteristics to the overall balance.

Flavor components

• Briny base: Kalamata olives (fruity, complex), green olives (sharp, salty), capers (pungent, acidic)
• Fresh contrast: Cherry tomatoes (sweet acidity), red onion (sharp crunch), parsley (clean freshness), dill (anise-like brightness)
• Liquid balance: Olive oil (richness carrier), lemon juice (acidic sharpness)
• Texture elements: Chopped olives (meaty bite), diced tomatoes (juicy pop), minced onion (crisp texture)

Let the salsa sit 10-15 minutes before serving to allow flavors to meld. The salt in the olives will draw moisture from the tomatoes and onions, creating a light natural dressing.

Timing & serving suggestions

Common mistakes (and quick fixes)

• Overcooked fish: Baked too long or oven too hot. Use thermometer and check early. If overcooked, serve with extra salsa and lemon to add moisture.
• Watery fish: Not patted dry or overcrowded pan. Ensure dry surface and space between fillets. Pour off excess liquid before serving.
• Bland fish: Insufficient seasoning or poor quality fish. Season aggressively and source fresh fish. The marinade should be flavorful on its own.
• Soggy bottom: Too much marinade pooling underneath. Brush on marinade rather than pouring. Use rack in baking dish if available.
• Bitter salsa: Over-processed olives or too much lemon pith. Chop olives by hand, not food processor. Use only lemon juice, not bitter pith.
• Separated salsa: Ingredients too wet or improperly chopped. Drain olives and tomatoes well. Uniform chopping ensures even distribution.
• Sticking to pan: Insufficient oil or wrong pan surface. Use well-oiled baking dish or parchment paper. Non-reactive pans prevent metallic flavors.

Substitutions & variations

Any substitution may affect cooking time, texture, and flavor balance. When substituting fish types, adjust cooking time based on thickness and oil content.

Equipment notes

• Baking dish: Glass or ceramic conducts heat evenly. Metal pans may cause hotter spots. Size should accommodate fillets without crowding—9×13 inch works for 4 fillets.
• Oven thermometer: Crucial for accuracy. Home ovens often run 25°F hot or cold, significantly affecting delicate fish cooking times.
• Instant-read thermometer: Most reliable doneness indicator. Insert into thickest part of thickest fillet, avoiding contact with baking dish.
• Cutting tools: Sharp chef’s knife for herb chopping. Olive pitter for efficient olive preparation. Microplane for lemon zesting.
• Mixing bowls: Small for marinade, medium for salsa. Non-reactive materials (glass, stainless) prevent metallic flavors from acidic ingredients.
• Paper towels: Essential for drying fish thoroughly. Moisture is the enemy of properly baked fish texture.
• Baking rack: Optional but helpful for air circulation. Elevates fish above any accumulated juices, preventing steaming.

Storage & reheating

• Refrigeration: Store leftover fish and salsa separately up to 2 days. Fish keeps better without salsa moisture. Cover tightly to prevent odors.
• Freezing: Freeze baked fish only (no salsa) up to 1 month. Wrap tightly in plastic then foil. Thaw in refrigerator overnight.
• Reheating fish: Best served cold or gently warmed. To reheat, place in 300°F oven 8-10 minutes until just warm. Microwave makes rubbery.
• Salsa storage: Best used fresh. If storing, drain excess liquid and use within 24 hours. The tomatoes will continue to release moisture.
• Make-ahead: Prepare salsa components separately, combine just before serving. Marinate fish up to 30 minutes before baking—longer and lemon juice will “cook” the fish.
• Leftover uses: Flake cold fish into salads. Use salsa as bruschetta topping. Combine with pasta for quick meal. Add to omelets or frittatas.

FAQ

Can I use frozen fish fillets?

Yes, but thaw completely in refrigerator overnight and pat very dry. Frozen fish releases more moisture during cooking, so increase baking time by 1-2 minutes and watch carefully.

My fish is sticking to the pan—what can I do?

Ensure adequate oil in marinade and use non-stick spray on baking dish. Let fish rest 2-3 minutes after baking—it will release naturally. Use thin spatula for removal.

Can I make this with skin-on fish?

Yes, but place skin-side down and don’t flip. The skin protects the flesh and becomes crisp. Increase baking time slightly for thicker skin varieties.

How do I know when the fish is done?

The fish should flake easily when tested with a fork at the thickest part, but still appear moist. The internal temperature should read 145°F. It will continue cooking slightly after removal.

Can I prepare the salsa ahead of time?

Yes, but combine all ingredients except tomatoes and herbs. Add those just before serving to maintain freshness and texture. Drain excess liquid if it sits more than an hour.

What if I don’t have fresh herbs?

Use 1/3 the amount of dried herbs in the marinade. For the salsa, the fresh herbs are essential—substitute with 1 teaspoon each dried parsley and dill, but flavor will be different.

Can I cook this at a different temperature?

Yes—375°F for 14-16 minutes (slower, more even) or 425°F for 8-10 minutes (faster, crisper exterior). Adjust time based on thickness and watch carefully.

Cook notes

1. Dry fish thoroughly
2. Check early, check often. Fish goes from perfect to overcooked in minutes. Use visual and temperature cues rather than strict timing.
3. Let fish rest
4. Taste salsa before serving
5. Serve immediately
6. Don’t overcrowd the pan
7. Use fresh lemons