Cut aubergine into quarters length ways and then each piece into 1" pieces.
Cut the courgette in half then into 1" pieces.
Cut peppers in 1" squares and chop red onion.
Mix the vegetable pieces together into a bowl with the olive oil, crushed garlic and seasoning. Pour into a roasting dish and cook in the oven for 35-40 minutes. Remove from the oven and stir in the chopped tomatoes and put back into the oven for a further 5 minutes.