Heat the oil in a large saucepan, add the onion and garlic and fry for 2 minutes. Stir in the curry paste and fry for 1 minute more.
Add the vegetables and fry for 2–3 minutes, stirring occasionally, then add the tomatoes and coconut milk. Stir well and bring to the boil, then lower the heat and simmer for 12–15 minutes until all the vegetables are cooked. Stir in the coriander and serve with rice.