Finely slice half the tomatoes and quarter the other half, keeping each batch separate.
Heat 2 tbsps of the oil in a large saucepan over a gentle heat. Add the garlic, stir and when lightly browned add the onions and a little salt. Cook, stirring from time to time, until the onions are soft.
Add the green chile and ginger then lower the heat and cook for one minute. Stir in the chile powder, coriander, crushed cumin and turmeric followed by the sliced tomato and tomato puree. Cook for 5 minutes stirring constantly. Add the quartered tomatoes and cook for a further 5 minutes.
Remove the pan from the heat and slowly mix in the yoghurt. Cover and set aside.
Heat the remaining oil in a small frying pan. Add the mustard seeds and when they begin to pop add the dried chillies and curry leaves. Cook for 1 minute then pour over the tomato curry and mix well. Reheat gently before serving.