Pat the tilapia filets dry with paper towels. Place fish in a 9x13 baking dish. It is okay if they are not in a single layer. They will still cook if they overlap slightly.
Arrange the tomatoes, sliced onion, sliced lemon, garlic and capers on top of the fish and along the sides of the dish.
Drizzle everything with extra virgin olive oil. Sprinkle sea salt evenly across the fish and vegetables. Sprinkle with cracked black pepper, if desired. Roast for 40 minutes.
Plate the fish and spoon the roasted cherry tomatoes and remaining juices over top.