Toast pine nuts in a skillet for 2 minutes or until brown and fragrant - gently toss them around so they don't burn. In a food processor or blender add the lemon juice, pine nuts, basil and olive oil. Pulse together to make a slightly textured pesto. Cover the broiler pan with aluminum foil and spray with olive oil. Then place the flounder fillets in a single layer and Spread the pesto over the fillets. Place the tray about 6" from the broiler and cook about 10 minutes, or until opaque in color and can be flaked with a fork.