Cut the eggplant in half and throw over a drizzle of olive oil, the crushed garlic and salt and bake for 30 minutes. Sautee the cherry tomatoes and sprint onions in a pan for 3-5 minutes, add the balsamic vinegar and cook for another 3 minutes.
Remove from the heat and set aside. Take the eggplant out of the oven and top with the tomato mixture and sliced mozzarella.
Return to the over for a further 10 minutes and serve.