Ingredients
1 tablespoon fresh thyme leaves
Finely grated zest of 1 lemon, plus wedges for serving
Fleur de sel and freshly ground pepper
4 mahi-mahi, striped-bass, or grouper fillets (each 6 ounces), skins removed
Extra-virgin olive oil, for drizzling
4 hoagie or other soft rolls, split
4 leaves Boston or Bibb lettuce, for serving
1 large tomato, sliced, for serving
1/2 cup mayonnaise
2 tablespoons chopped dill pickles
1 tablespoon white-wine vinegar
1 tablespoon capers, drained, rinsed, and chopped
1 teaspoon Dijon mustard
1 tablespoon chopped scallion
Kosher salt
Preparation
For the Sandwich: Combine thyme, lemon zest, 1 teaspoon salt, and 1 1/2 teaspoons pepper in a small bowl. Sprinkle mixture over all sides of fillets.
Preheat grill to medium-high. Drizzle fillets with oil, then grill, flipping halfway through, until opaque and cooked through, 4 to 5 minutes a side. Transfer to a plate. Grill rolls, cut-sides down, until toasted and golden, about 30 seconds.
For the Tartar Sauce: Combine all ingredients in a bowl and season with salt. (Sauce can be refrigerated in an airtight container up to 3 days.)
Top bottom half of each roll with tartar sauce, a fish fillet, lettuce, and tomato; add top halves and serve.
