Mix the beef, onion slices, garlic, ginger and onion pastes, red chili, coriander and turmeric powders, salt, mustard oil, cinnamon sticks, cardamoms, cloves and bay leaves. Heat a saucepan and add this mixture. Pour in 2 cups of water.
Cook for about 18 minutes. Check if the beef has started to soften. If it has, then heat the soya bean oil on a separate pan and add the sliced onions. Stir until the onions turn golden brown.
Sprinkle the garam masala powder. Add the fried onions to the beef mixture.
Mejban er Mangsho is now ready to be served with pulao or fried rice.