Combine oil and garlic in a baking dish and place dish in the oven. Preheat oven to 450 degrees C (232 degrees C).
Remove baking dish from the oven when the garlic is lightly browned, after about 10 minutes. Continue preheating the oven.
Add tomatoes, capers, olives, red pepper and red wine vinegar to the baking dish. Squeeze one lemon half over the mixture and season with crushed red pepper and black pepper.
Place sardines, along with the marinade from the cans, on top of the tomato mixture and return to the oven.
Bake in the preheated oven until sardines are browned on top and tomatoes have softened, 15 to 20 minutes.
Sprinkle feta on top and turn oven to broil. Broil until feta is lightly browned, 2 to 3 minutes. Sprinkle with parsley and squeeze remaining lemon half over the top.