- Preheat oven to 350 degrees F (175 degrees C).
- Arrange flounder in a shallow baking dish, and coat with the lemon juice. Season with rosemary, salt, and pepper. Top with lemon slices. Pour water into the dish.
- Bake for 30 to 40 minutes in the preheated oven, or until easily flaked with a fork.
- In a medium bowl, mix pineapple, onion, garlic, jalapeno, tomato, pineapple juice, red bell pepper, and yellow bell pepper. Cover, and refrigerate while fish is baking. Top fish with salsa to serve.
Aluminum foil can be used to keep food moist, cook it evenly, and make clean-up easier.