Grilled Fish Yassa with Mustard-Onion Marinade
A tangy and flavorful grilled fish dish marinated in a citrusy mustard and caramelized onion sauce, a classic from Senegal’s coastal cuisine. This african-inspired seafood ready in about 40 minutes blends large onions, thinly sliced, lemon juice, Dijon mustard into a versatile sauce that lifts everything from grain bowls and roasted vegetables to grilled proteins — a small-batch staple worth keeping in the fridge. Each serving lands at about 320 calories and feeds 4, so a small batch covers several meals across the week without taking over the fridge. 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.
Ingredients
- 1.5 lbs whole white fish (such as snapper or tilapia), cleaned and scaled
- 3 large onions, thinly sliced
- 1/2 cup lemon juice
- 3 tbsp Dijon mustard
- 1/4 cup vegetable oil
- 3 garlic cloves, minced
- 1 1/2 tsp salt
- 1 tsp black pepper
- 1 tsp dried thyme
- 1 bay leaf
- 1/2 cup water
Instructions
- Step 1: In a large bowl, combine 1/2 cup lemon juice, 3 tbsp Dijon mustard, 1/4 cup vegetable oil, 3 minced garlic cloves, 1 1/2 tsp salt, 1 tsp black pepper, and 1 tsp dried thyme. Whisk until smooth.
- Step 2: Add 3 large thinly sliced onions and 1 bay leaf to the marinade, tossing to coat evenly. Place the 1.5 lbs whole cleaned white fish in the marinade, turning to coat thoroughly. Cover and refrigerate for at least 2 hours, preferably overnight.
- Step 3: Preheat grill to medium-high heat (about 400°F). Remove fish from marinade, reserving the marinade and onions.
- Step 4: Grill the fish for 6-8 minutes per side, brushing occasionally with reserved marinade until the flesh is opaque and flakes easily with a fork.
- Step 5: Meanwhile, pour reserved marinade and onions into a skillet with 1/2 cup water and simmer over medium heat for 10 minutes until onions are tender and sauce slightly thickened.
- Step 6: Serve grilled fish topped with the cooked mustard-onion sauce.
Equipment for this recipe
Top-rated tools to make this recipe successfully.
Frequently asked questions
How long does Grilled Fish Yassa with Mustard-Onion Marinade take to make?
Total time is about 40 minutes (15 min prep + 25 min cook). A small batch typically covers several meals in the week — store as the recipe directs.
How do I store leftover Grilled Fish Yassa with Mustard-Onion Marinade?
Transfer to an airtight jar and refrigerate for up to 5–7 days. Most sauces freeze well for up to 2 months — portion into small containers or freezer bags so you can thaw only what you need. Stir before serving; cream- or yogurt-based sauces may separate on standing.
Can I substitute ingredients in Grilled Fish Yassa with Mustard-Onion Marinade?
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 Grilled Fish Yassa with Mustard-Onion Marinade 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 Grilled Fish Yassa with Mustard-Onion Marinade?
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.
