This is a recipe that I acquired from a North Indian cookery tutor several years ago. We used to put it in at the end of the cook although to be honest it did have a tendency to take over the curry so I used to add only half a tsp. After reading through several threads I think I will try adding to a mix powder where GM is required.
Two tbsp each of:
Large black cardamons (husks removed, use only the resinous seeds inside)
Small green cardamons (left whole)
Cloves
Half a Cinnamon stick
Whole black peppercorns
Grind in a spice/coffee grinder, store in an airtight jar.