In a large pot over medium heat, melt 2 tablespoons butter. Add 1 cup long-grain brown rice and cook, stirring frequently, for 5 minutes until the rice is lightly toasted and coated in butter.
Add 1/2 cup diced sweet onion and cook, stirring occasionally, until the onion is softened, about 3–4 minutes.
Stir in 1 minced garlic clove and cook 1 minute until fragrant.
Add 1 teaspoon cumin, 1 teaspoon chili powder, 1/2 teaspoon black pepper, and 1/2 teaspoon kosher or sea salt; stir to combine.
Stir in 1 tablespoon tomato paste, 1/2 cup diced fire-roasted tomatoes (with liquid), and 2 tablespoons diced green chiles (with liquid), mixing until the tomato paste is evenly distributed.
Pour in 2 cups chicken broth (fat-free) and bring the mixture to a boil over medium-high heat.
Reduce heat to low, cover the pot, and simmer gently until the rice is tender and most of the liquid is absorbed, about 20 minutes (some long-grain brown rice may need a few extra minutes).
Remove from heat, keep covered, and let rest for 5 minutes. Fluff with a fork and serve.