In a 3-quart pot over high heat, sauté butter, onions, mustard seeds, cumin, and ginger until onions are golden brown. Add tomatoes and reduce heat to medium, then cook tomatoes down for about 5 minutes. Add tomato paste and mix well. Add rice and stock and bring to a boil, turn heat to low, tightly cover, and cook until liquid is absorbed, about 12 minutes, making sure to not remove lid. Turn off heat, keep lid on and let sit for another 10 minutes, then lift lid and use a fork to fluff rice.
From Tiny Grains, Big Meaning.