1. Preheat oven to 400 degrees F (200 degrees C).
2. Wash cod fillets and pat dry with paper towels. Place in a baking dish.
3. Season with salt and pepper on all sides. Brush the tops with olive oil and squeeze some lemon juice over the fillets.
4. Lay tomato slices down the length of each fillet, sprinkle with garlic and basil.
5. Cover with foil and bake in the preheated oven until the fish flakes easily with a fork, 15 to 20 minutes.