Breaded Flounder with Roasted Tomatoes

Here Dijon mustard serves a dual purpose: It flavours the delicate fish, and helps the breadcrumb coating stay in place as the fish cooks. Tilapia can be used in place of the flounder.

6 plum tomatoes, halved lengthwise
2 Tbsp. olive oil, plus more for one of the baking sheets
¾ tsp. dried tarragon
pinch sugar
sea salt
black pepper, freshly cracked
1/3 cup mayonnaise
1 Tbsp. fresh lemon juice
3 slices white sandwich bread (about 1 oz each), torn into large pieces
4 flounder fillets (1½ lbs total)
2 Tbsp. Dijon mustard

Preheat oven to 450°F, with racks in upper and lower thirds.

Place tomatoes on a rimmed baking sheet. Sprinkle with 1 Tbsp. oil, tsp. tarragon, sugar, salt, and pepper; toss to coat. Arrange tomatoes cut side up. Roast on lower rack until tender, 20-25 minutes. (Keep oven on for fish.)

Meanwhile, make sauce: In a small bowl, whisk together mayonnaise, remaining ½ tsp. tarragon, and lemon juice; season with salt and pepper. Set aside.

Line a rimmed baking sheet with aluminum foil and brush with oil. In a food processor, place bread, a pinch each salt and pepper, and remaining Tbsp. oil; pulse until fine crumbs form.

Lay fillets flat on prepared baking sheet; season with salt and pepper. Spread top sides with mustard; sprinkle with bread crumbs, pressing to adhere.

Bake on upper rack until fish is cooked through and crumbs are browned, 6-8 minutes.

Serve with tomatoes and sauce.

Makes 4 servings.