- Preheat the oven to 450 degrees F (232C).
- Season the fish with pepper and a dash of salt if desired. Arrange 4 large sheets of aluminum foil on a work surface and place 1 fish filet on each piece of foil.
- Arrange zucchini, squash, and onion around each filet and season with salt and pepper.
- Drizzle 1⁄2 tablespoon oil and 1⁄2 tablespoon lemon juice onto vegetables and fish.
- Arrange a few lemon slices on top of each filet and top each piece with 1⁄2 teaspoon dried basil.
- Wrap foil around fish and vegetables, leaving some air space within each packet, and seal very well.
- Set packets on a rimmed baking sheet and bake for 8 minutes. Carefully open 1 packet to check fish and test with a fork to see if it flakes easily.
- Serve immediately using caution when opening the packets as the steam will be very hot.
Substitution Tip: Just about any type of fresh or dried herb works well with fish. Some good options for white fish include: parsley, ginger, cumin, coriander, and cayenne.