Rinse and soak beans for a couple of hours in at least 3 1/2 cups of water in a medium saucepan. Bring beans to a boil over medium heat, add half the ginger, the chili powder, and the tumeric. Reduce heat, cover the pan and cook slowly for 45-50 minutes Add remaining ginger, chilis, tamarind pulp, mix it well and let it simmer for another 10-15 minutes. Meanwhile, SLOWLY dryfry onion to gradually carmelize it, as it begins to color add cumin seeds and garlic (add a little H2O to prevent burning if necessary). Remove pan from heat just as garlic darkens. Pour mixture into beans, together with Garam masala, stir and cook another 5 minutes. Before serving, stir in cilantro leaves and serve hot.