In a large pot, heat the olive oil over medium heat. Add the chopped red onion and jalapeños (if using), and sauté until the onion is translucent and fragrant, about 5-7 minutes. Stir in the minced garlic and ground cumin, cooking for an additional minute until the garlic is fragrant.
Add the rinsed rice to the pot, stirring well to coat it with the oil and spices. Cook for about 2 minutes, stirring frequently.
Carefully pour in the low sodium chicken broth. If you’re using black beans, add them now along with the mild diced green chilies. Stir everything together, ensuring that the rice is submerged in the liquid.
Increase the heat and bring the mixture to a boil. Once boiling, reduce the heat to low, cover the pot, and let it simmer for about 18-20 minutes, or until the rice is cooked and has absorbed the liquid.
Once the rice is cooked, remove the pot from the heat. If you’d like, stir in the butter for added richness. Fluff the rice gently with a fork, then mix in the chopped cilantro and lime juice. Season with freshly cracked salt and pepper to taste.