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Seared Fish Sandwich with Tarragon Yogurt
This simple fish sandwich is perfect for quick summer weeknight dinner.
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In this recipe, mahi-mahi fillets are coated in herbs, then sautéed in a mix of oil and butter to bring out their rich, fresh flavor. The seared filet of fish is tucked into a sandwich with a bright and refreshing tarragon yogurt sauce and tangy pickled shallots, keeping things simple yet flavorful. I like using a yogurt-based sauce here instead of mayonnaise—it’s lighter, tangier, and lets the fish shine. For another simple fish recipe, try this pan-seared white fish.
Table of contents
Key Ingredients in This Recipe
- Mahi mahi – I use filets of mahi mahi for this sandwich. The fish has a mild flavor and firm texture which makes it great for serving on a sandwich since it holds together well. It has a texture similar to swordfish making it or Opah a great option if a substitute is needed.
- Shallots – Shallots have a mild, slightly sweet flavor. If needed swap in yellow or red onion in this recipe. They are quickly pickled to add a slightly acidic onion-y flavor to the sandwich. The general rule of thumb is 3 medium shallots equal 1 medium onion. Red quick pickled onion can also be used in this recipe.
- Greek Yogurt – How does Greek yogurt differ from regular yogurt? It’s strained to remove any excess whey – resulting in a richer, creamier consistency yogurt. Full-fat (5% fat) Greek yogurt is combined with tarragon, lemon zest and juice, garlic powder, salt and pepper.
- Lemon zest – The lemon zest is the grated outer skin from the lemon. Use a zester or microplane to remove the zest. If you don’t have a zester use a paring knife or vegetable peeler to remove the rind and finely chop it.
full ingredient list with exact amounts can be found in the recipe card below.
How to Make this Seared Fish Sandwich Recipe
Step 1: Make the pickled shallots.
In a small saucepan, bring apple cider vinegar, ½ cup water, salt, and sugar to a boil. Place sliced shallots in a bowl or jar, then pour the hot liquid over them. Cover and refrigerate for at least 2 hours. (They’ll keep in the fridge for up to 2 weeks.)
Step 2: Make the tarragon yogurt sauce.
In a small bowl, mix yogurt with tarragon, lemon zest and juice, garlic powder, salt, and pepper. Cover and chill until ready to use.
Step 3: Season the fish.
Season the filets on both sides with salt and pepper. Sprinkle with the herbs on both sides.
Step 4: Cook the fish.
Heat 1 tablespoon olive oil in a large pan over medium heat, then add 1 tablespoon butter. Working in batches, sauté fillets until golden, about 3 minutes. Flip and cook another 3 to 4 minutes. Remove and repeat with remaining fillets.
Step 5: Assemble sandwiches.
Add the lettuce leaves to the bottom halves of the toasted rolls, then top each roll with a piece of the fish followed by some pickled shallot. Spread about 2 tablespoons of the yogurt on the top of each roll then close the sandwiches.
Tips and Tricks for This Recipe
Swaps and Substitutions
- Swap the mahi-mahi filets for another firm fish like Opah or swordfish.
- Try swapping the Greek yogurt sauce for a combination of mayonnaise and vinegar-based hot sauce for another delicious sauce option.
Other Recipes to Try
If you enjoy this seared fish sandwich recipe, I recommend checking out some of these:
Check out these other fish recipes:
Made this dish? Be sure to rate the recipe and drop a comment below! Your feedback means everything (and helps others find it too)!
Seared Fish Sandwich with Tarragon Yogurt
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Ingredients:
For the pickled shallots:
- 2 large shallots, thinly sliced
- ½ cup apple cider vinegar
- 2 teaspoons kosher salt
- 2 teaspoons granulated sugar
For the tarragon yogurt sauce:
- 1 cup Greek yogurt
- 2 tablespoons freshly chopped tarragon
- 2 teaspoons lemon zest
- 2 tablespoons freshly squeezed lemon juice
- ½ teaspoon teaspoon garlic powder
- ¼ teaspoon kosher salt
- ¼ teaspoon freshly ground black pepper
For the fish sandwich:
- 4 (6-ounce) filets mahi mahi fillet
- Kosher salt, to taste
- Freshly ground black pepper, to taste
- 2 tablespoons chopped flat-leaf parsley
- 2 tablespoons chopped tarragon
- 1 tablespoon chopped chives
- 2 tablespoons extra-virgin olive oil, divided
- 2 tablespoons unsalted butter, divided
- 4 ciabatta buns, split and toasted
- 8 leaves green leaf lettuce
Instructions:
For the pickled shallots:
- In a small saucepan over medium heat, stir together the apple cider vinegar, ½ cup water, salt and sugar and bring to a boil. Add the shallots to a small bowl or glass jar and pour the pickling mixture over top. Cover and refrigerate at least two hours before using. The pickled shallots can be kept in an airtight container in the pickling liquid for up to 2 weeks.
For the tarragon yogurt sauce:
- Add the yogurt to a small mixing bowl and stir together the tarragon, lemon zest, lemon juice, garlic powder, salt and pepper. Cover and refrigerate until ready to use.
For the fish sandwich:
- Season the filets on both sides with salt and pepper. Sprinkle with the herbs on both sides.
- Heat a large sauté pan over medium heat, add 1 tablespoon of the olive oil and heat through. Add 1 tablespoon of the butter and allow to melt. Working in batches, add 2 filets to the pan and sauté until golden brown, about 3 minutes. Use a spatula to flip the fish and sauté on the other side, about an additional 3 to 4 minutes depending on the thickness. Remove to a plate then repeat with the remaining oil, butter and fillets.
- Add lettuce leaves to the bottom halves of the toasted rolls, then top each roll with a piece of the fish followed by some pickled shallot. Spread about 2 tablespoons of the yogurt on the top of each roll then close the sandwiches.
Nutrition:
Calories: 537kcal | Carbohydrates: 37g | Protein: 58g | Fat: 18g | Saturated Fat: 6g | Polyunsaturated Fat: 2g | Monounsaturated Fat: 8g | Trans Fat: 0.2g | Cholesterol: 131mg | Sodium: 1729mg | Potassium: 1065mg | Fiber: 2g | Sugar: 5g | Vitamin A: 822IU | Vitamin C: 12mg | Calcium: 174mg | Iron: 4mg
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