Spiced Senegalese Fish Yassa with Caramelized Onions and Mustard Sauce

By , Test Kitchen Director · Reviewed by AislePrompt Editorial · ·

Fish fillets marinated in a vibrant mustard-lemon sauce, then pan-seared and served atop a bed of slowly caramelized onions packed with Senegalese spices. This African-inspired seafood recipe, ready in about 40 minutes, pairs yellow onions, thinly sliced, fresh lemon juice, Dijon mustard for a weeknight-friendly dinner that comes together with one pan and minimal cleanup. Each serving lands at about 320 calories and feeds 4, so it slots cleanly into a weekly meal plan and pairs well with a quick salad or grain on the side. Tap "Plan a meal with the AI" below to drop this recipe into your week and send the ingredients straight to Instacart. Nutrition values are approximate, calculated from USDA FoodData Central (fdc.nal.usda.gov) — verify against ingredient labels for any health-driven dietary plan.

Prep: 10 min Cook: 30 min Serves 4 African cuisine 320 cal/serving
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Ingredients

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Instructions

  1. Step 1: In a bowl, whisk together 1/3 cup fresh lemon juice, 3 tbsp Dijon mustard, 3 minced garlic cloves, 1 1/2 tsp salt, 1 tsp black pepper, and 1/2 tsp smoked paprika. Add 4 white fish fillets and coat them thoroughly. Marinate for 30 minutes.
  2. Step 2: Heat 3 tbsp vegetable oil in a large skillet over medium heat. Add 2 large thinly sliced yellow onions and 1 finely chopped scotch bonnet pepper (optional). Cook for 15 minutes, stirring occasionally, until onions are deeply caramelized and soft.
  3. Step 3: Remove onions from skillet and set aside. Add 1 tbsp vegetable oil to the same skillet and heat over medium-high heat. Add marinated fish fillets and sear for 4-5 minutes per side until golden and cooked through.
  4. Step 4: Serve fish fillets on a bed of the caramelized onions, spooning any pan juices over the top for added flavor.

Frequently asked questions

How long does Spiced Senegalese Fish Yassa with Caramelized Onions and Mustard Sauce take to make?

Total time is about 40 minutes (10 min prep + 30 min cook). Most home cooks find this fits comfortably into a weeknight; double the batch on Sunday for two dinners.

How do I store leftover Spiced Senegalese Fish Yassa with Caramelized Onions and Mustard Sauce?

Refrigerate in a covered airtight container for up to 3–4 days (FDA FoodKeeper guideline for cooked fish). Store any fresh salsa or citrus-based garnish in a separate container — it keeps for up to 2 days. Freeze cooked fish (without fresh garnishes) for up to 3 months; thaw overnight in the fridge and reheat gently at 275°F until just warmed through to preserve texture.

Can I substitute ingredients in Spiced Senegalese Fish Yassa with Caramelized Onions and Mustard Sauce?

Yes — most ingredients in this recipe have flexible swaps. For oil, use any neutral high-smoke-point oil (avocado, grapeseed, refined coconut). For aromatics, dried herbs at ⅓ the volume of fresh work in a pinch. The full ingredient list is shoppable on Instacart so you can see substitutes in real time.

How do I scale Spiced Senegalese Fish Yassa with Caramelized Onions and Mustard Sauce for a different number of people?

The recipe is written for 4 servings. Multiply each ingredient by (your serving target / 4). Cook time stays roughly the same up to 2x; for 3-4x batches, switch from a skillet to a sheet pan or stockpot so the food isn't crowded — overcrowding steams instead of browns.

What goes well with Spiced Senegalese Fish Yassa with Caramelized Onions and Mustard Sauce?

African seafood like this pair well with a simple grain (rice, couscous, or crusty bread), a quick salad with acid (lemon vinaigrette, pickled onions), and a pan sauce or yogurt-based dip. Tap "Plan a meal with the AI" to get specific side suggestions.

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