Heat olive oil in a pot over medium heat. Add diced onion and sauté for 3 minutes until softened. Add minced garlic and cook for another minute.
Stir in the rice, cumin, chili powder, and salt. Cook for 2 minutes, allowing the rice to absorb the flavors.
Pour in the chicken broth and place the halved jalapeño (if using) in the pot. Stir well, bring to a boil, then reduce heat to low. Cover and let simmer for 15 minutes.
Remove the jalapeño, then gently fold in the black beans, lime juice, and chopped cilantro. Cover and let sit for 3-5 minutes.
Fluff with a fork and serve warm.