Dry roast all the ingredients (and as always, take care not to burn). Cool and grind to a fine powder. When dry roasting spices, remove from the pan onto a parchment or baking paper after switching off flame. Never leave it in the same pan itself as the spices continue to roast in the residual heat.
To prepare the curry:
In a deep pan or pressure cooker, heat oil and add the onions, garlic and ginger. Saute till the onions have caramelized well.
Add the tomatoes and continue to cook till the tomatoes turn mushy.
Turn down the heat and add all the spices. Continue to cook for another 2 minutes.
Add the washed and soaked beans along with a tea bag (use an ordinary tea bag and not the flavoured ones). Adding the tea bag is optional; this is only to lend the deep dark colour to the dish and does not really add much flavour to the dish.
Season with salt and add 2 cups of water. Cook till the beans are done to the consistency you like.
Remove from heat and garnish with fresh coriander leaves.
Serve hot with rice or flat breads.
Notes
Store the excess spice blend in an airtight container for future use.