Mediterranean Fish in Romesco Sauce

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Table of contents:

• How to Make Mediterranean Fish in Romesco Sauce – Romesco de Peix
  • Ingredients
  • Equipment
  • Instructions
    • Step 1 – Prepare the romesco sauce
    • Step 2 – Prepare the fish stew
    • Step 3 – Bake
    • Step 4 – Serve
• Origin of this recipe
  • What is Romesco de Peix?
• Romesco Sauce
  • Traditional and Modern Uses for Romesco Sauce
  • Traditional
  • Modern (and globally popular) Uses
• FAQs
  • Can I use frozen fish?
  • Is this recipe gluten-free?
  • Can I make the Romesco sauce ahead of time?
  • How spicy is the dish?
  • Can I use different nuts in the sauce?
  • What should I serve with this dish?
• More Mediterranean Dips and Sauces
• Choosing the Best Fish for This Recipe
• More Mediterranean Fish Recipes
• Storage and Reheating Tips
• Nutrition Facts (Per Serving)

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How to Make Mediterranean Fish in Romesco Sauce – Romesco de Peix

Ingredients

For the fish

• 35 oz. 1kg fish fillets, scaled with skin on (we used Spanish Gallineta (Rosefish/scorpion fish)
• 2 small onions, sliced fine
• Extra virgin olive oil
• Salt and pepper for seasoning
• Small handful of parsley, finely chopped for garnish

For the romesco sauce (Makes approx. 400ml /13fl. oz.)

• 200 g/7oz. cashews or blanched almonds 
• 200 g/7oz. roasted red piquillo peppers from a jar 
• 2 tomatoes grated, and skin removed
• 4 garlic cloves
• 1 tbsp Sherry Vinegar
• 1 tsp Spanish La Vera Smoked Paprika
• 1 tsp of Cayenne Pepper (add more for extra spicy)
• Extra virgin olive oil (approx 80ml)
• Salt to taste (we used around 1 tsp)
• Cracked black pepper to taste (we used around ½ tsp)

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Equipment

• 1 large 12-inch (30cm) Casserole Dish or oven tray
• Food processor or blender to make the romesco sauce
• Oven
• Wooden Cutting Board
• Box Grater
• Chef Knife

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Instructions

Step 1 – Prepare the romesco sauce

• In a dry pan, lightly toast the Cashews (or almonds) on medium-high heat for 5 minutes. Stir frequently to stop them from burning. 
• The nuts should start to blacken slightly. Allow almonds to cool before moving on to the next step.
• Add the roasted red peppers, grated tomato, garlic, vinegar, smoked paprika, and cayenne pepper, into a blender or food processor along with the toasted nuts. 
• Season to taste with salt and pepper and add a good glug of olive oil.
• Buzz for around 2-3 minutes or until smooth (there should still be a loose nutty texture to the sauce). 

Step 2 – Prepare the fish stew

Preheat oven to 180°C/350°F

• Slice the fish fillets into inch-long strips, cutting the fish skin side down. Add the fish directly to a large casserole dish.
• Finely slice the onion and add to the dish with the fish. 
• Pour the romesco sauce over the fish and onions and give everything a mix so all is evenly covered.
• Drizzle with a little olive oil and season with a little freshly cracked black pepper. 

Step 3 – Bake

• Bake on the middle shelf of the oven for 20-25 minutes. 

Step 4 – Serve

• Garnish with some freshly chopped parsley and serve while hot with plenty of fresh bread.

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Origin of this recipe

This recipe draws inspiration directly from a Catalan (Spanish)  dish by the name of Romesco de Peix. This Catalan Fish Stew uses a rich and flavorful Romesco Sauce and fresh chunks of fish, some onion, and plenty of homemade romesco sauce. 

The dish is nutty, savory, smoky, and has just a pinch of heat to it thanks to the use of cayenne pepper. We make our dish mild on the heat scale so the other flavors can shine through. 

What is Romesco de Peix?

Romesco de Peix is a traditional Catalan fish stew from the coastal region of Tarragona in northeastern Spain. The name literally translates to “fish with Romesco”, highlighting the starring role of the region’s iconic sauce. Historically, fishermen prepared the dish onboard using whatever fresh catch they had, simmering it together with a rich Romesco made from roasted peppers, nuts, tomatoes, garlic, bread, and olive oil.

The result is a warm, rustic stew that’s smoky, nutty, and deeply Mediterranean. Unlike other Spanish fish stews, Romesco de Peix relies on the sauce itself for thickness and flavor—no stock or wine needed. Each family has its own variation, but the combination of tender fish and bold Romesco is unmistakably Catalan and has become a staple of local coastal cuisine.ed.

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Romesco Sauce

Romesco sauce (in Catalan, salsa romesco) comes from Catalonia, a region in northeastern Spain, particularly around the city of Tarragona. Its origins are tied to the fishermen who worked along the Catalan coast. Legend has it that they created the sauce as a flavorful accompaniment to the day’s catch, using ingredients that were readily available and shelf-stable.

Romesco is also a staple ingredient during the season of Calçots, a type of large green onion harvested at the end of winter and celebrated by cooking them over wood fires or coals until the blacken. The Calçots are then served alongside homemade romesco sauce for dipping. 

Romesco reflects classic Mediterranean flavors: nuts, peppers, olive oil, and garlic, combined into a rustic, hearty condiment.

Traditional and Modern Uses for Romesco Sauce

Romesco is very versatile. Common uses include:

Traditional

• Seafood, especially grilled fish (its original use)
• Calçots, a type of green onion celebrated in the Catalan calçotada festival, where Romesco (or a close variation called salvitxada) is the classic dip
• Grilled meats and vegetables
  

Modern (and globally popular) Uses

Romesco is one of those sauces that once it’s on your radar, you’ll end up keeping some in the fridge at all times and literally start spreading it on everything. It really is a flavor that works well with pretty much everything! 

Here’s a few suggestions: 

• As a dip for bread or crudités
• Spoon over roasted potatoes, chicken, or shrimp
• As a sauce for grilled vegetables or grain bowls
• Spread on sandwiches and burgers
• Mixed into pasta for a smoky, nutty alternative to tomato sauce

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Choosing the Best Fish for This Recipe

This dish works best with firm, white fish that can hold its shape while baking in the Romesco sauce. Traditional Catalan versions often use local Mediterranean species like gallineta (rosefish) or rape (monkfish), but many widely available options work beautifully. Look for fish with a mild flavor and a firm, flaky texture.

Great choices include:

• Cod – widely available, mild, and flaky
• Haddock – slightly sweeter flavor
• Monkfish – firm, almost lobster-like texture that won’t fall apart
• Snapper or Sea Bream – richer flavor, great with Mediterranean sauces
• Sea Bass – tender and delicate, pairs well with smoky Romesco

Avoid very oily fish (like mackerel or sardines) or delicate types that break down quickly (like sole). Skin-on fillets are ideal, as they help hold the pieces together during baking and add extra flavor.

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Storage and Reheating Tips

This dish stores surprisingly well thanks to the robust nature of Romesco sauce.

Refrigeration:

• Store leftovers in an airtight container.
• Keeps well for 2–3 days.

Freezing:

• You can freeze it, but the texture of the fish may become softer.
• If freezing, use firm fish like monkfish or cod.
• Freeze for up to 2 months.

Reheating:

• Reheat gently in a pan over low heat for 5–7 minutes until warm.
• Avoid boiling or high heat, as fish can overcook and become tough.
• You can also reheat in a low oven at 150°C/300°F for about 10–12 minutes.

Tip: If the sauce thickens after storing, stir in a splash of water or olive oil to loosen it back to its original texture.

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Nutrition Facts (Per Serving)

Assuming 4 servings from the full recipe and based on standard ingredient nutritional data.

Nutrition Facts (per serving)	Amount	% Daily Value (DV)
Calories	~560 kcal	28%
Total Fat	38 g	49%
Saturated Fat	5 g	25%
Monounsaturated Fat	24 g	—
Polyunsaturated Fat	6 g	—
Cholesterol	95 mg	32%
Sodium	720 mg	31%
Total Carbohydrates	15 g	5%
Dietary Fiber	3 g	11%
Total Sugars	5 g	—
Protein	42 g	84%
Vitamin C	~45 mg	50%
Vitamin A	~1400 IU	28%
Calcium	70 mg	5%
Iron	2.5 mg	14%
Potassium	~950 mg	20%

Note: These are well-researched estimates based on common nutritional databases (fish fillets + nuts + peppers + olive oil). For publication, I can refine this further if you want to specify the exact fish type and amounts.

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FAQs

Can I use frozen fish?

Yes. Thaw it completely, pat it very dry, and proceed as normal. Drying helps the sauce cling and prevents excess liquid.

Is this recipe gluten-free?

Yes — as written, Romesco uses nuts rather than bread as a thickener. Just ensure your jarred peppers and spices are certified gluten-free.

Can I make the Romesco sauce ahead of time?

Absolutely. Romesco keeps 5–7 days in the fridge and freezes very well. Making it ahead makes the recipe even quicker.

How spicy is the dish?

It has a mild heat from cayenne pepper, but you can easily reduce or omit it. Romesco is meant to be balanced, not fiery.

Can I use different nuts in the sauce?

Yes. Almonds and hazelnuts are the most traditional, but cashews provide a wonderfully creamy, mellow texture. Walnuts add a deeper, earthier flavor.

What should I serve with this dish?

Fresh crusty bread is classic. It also pairs well with rice, roasted potatoes, couscous, or a simple green salad.

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