Melt the butter in a large pot or saute pan (with a lid) over medium-low heat, then stir in the onion and cook, stirring, for 3-4 minutes or until softened slightly.
Add the rice and cook, stirring constantly, until the rice just begins to turn golden - about 5 minutes.
Stir in the minced garlic, cumin, chili powder, cayenne and pepper and cook, stirring for 1 minute, then stir in the tomato sauce/paste and cook for 1 more minute.
Stir in the vegetable stock, increase the heat and bring to the boil. Reduce heat to low, cover the pan with the lid and simmer the Seasoned Rice for 20-25 minutes, or until the rice is cooked through. Check occasionally so the rice doesn’t scorch and add a little water if necessary.