Melt the butter in a pan, then cook onions for 1 min. Add the spices and cook for 30 seconds, stirring.
Add the tomatoes, eggs and yogurt, then cook, stirring, for about 4 mins until scrambled. Season to taste.
Spoon one quarter of the mixture onto one quarter of a warmed chapati. Fold in half, then in half again to make a triangle. Repeat with the remaining mixture and chapatis. Serve immediately, garnished with a little of the coriander.
Recipe from Good Food Vegetarian Christmas magazine, December 2006