Make the sauce
1 can makes about 880 g — enough for 7 New York piesBlend the tomatoes smooth in their juice. Melt the butter in a wide pan over medium heat and cook the onion 8–10 min, until soft and golden. Add the garlic and ginger for 1 min, then the garam masala and chili powder for 30 seconds. Pour in the tomatoes with the salt and sugar and simmer 20–25 min, stirring now and then, until a spoon drawn through it leaves a line. Blend it smooth again, stir in the cream and the crumbled methi off the heat, and let it cool before it goes on the dough. Keeps 4 days in the fridge.