For the flounder:
2. Preheat the grill to medium-high.
3. Spray the grill grate with non-stick cooking spray. Season the fillets with salt and pepper.
4. Grill each flounder fillet for about 3 minutes on each side, depending on the thickness of the fish, then season each fillet with the juice of one lemon wedge.
For the sandwiches:
5. Spread about 1 1/2 tablespoons of the dressing on each side of the roll. Next add two slices of lettuce leaves and tomato and top with the flounder. Season to taste.