How to Make It
In a food processor, finely chop the onion, garlic, ginger, cumin, chile, turmeric, cardamom and 1/2 teaspoon of black pepper. Add the water and pulse to make a soupy paste.
In a medium skillet, melt the butter. Add the paste and cook over moderate heat, stirring, until almost dry, 5 minutes. Add the stock and simmer over low heat, stirring, until the sauce is thickened, about 8 minutes.
In a large nonstick skillet, heat the oil. Season the liver with salt and pepper and cook over moderately high heat until browned on the bottom, about 2 minutes. Reduce the heat to moderate, turn the liver and cook until medium within, about 2 minutes. Add the liver to the sauce and simmer for 1 minute. Add the lemon juice and season with salt and pepper. Sprinkle with the cilantro and serve with rice.