Heat the oil in a large saucepan. Add the mustard seeds and as they begin to pop, add the onions and a little salt to taste and cook until soft. Add the ground coriander, turmeric and chilli powder. Mix well then add the tomatoes and 4 tbsp water and cook for 2 minutes. Stir in the peas and pepper. Cover the pan and cook for 15 minutes or until peas are tender. Mix in the fresh coriander (if using) and add more pepper to taste. Cook for a further 2 minutes then serve garnished with fresh coriander, if desired.

Serve hot with flat breads.