In a medium pot, combine the rice and vegetable broth (or water). Bring to a boil over high heat. Once boiling, reduce the heat to low, cover, and simmer for about 15-18 minutes, or until the rice is cooked and the liquid is absorbed.
Remove the pot from heat and let the rice sit covered for another 5 minutes.
While the rice is cooking, heat the olive oil in a large skillet over medium heat. Add the chopped onion and sauté for about 3-4 minutes until softened.
Add the minced garlic, cumin, chili powder, salt, and black pepper to the skillet. Cook for another minute, stirring constantly until fragrant.
Stir in the rinsed and drained black beans and corn. Cook for about 5-7 minutes, stirring occasionally, until heated through.
Once the rice is done, fluff it with a fork and add it to the skillet with the beans and spices. Gently mix everything until well combined.
Serve the rice and beans warm, garnished with fresh cilantro and lime wedges if desired.