In a large pot, heat a splash of oil over medium heat. Add finely chopped onions and minced garlic, stirring occasionally for about 3-4 minutes, until the onions become translucent and fragrant.

Sprinkle in the cumin and stir for about 30 seconds, allowing it to bloom and release its aromatic essence.

Pour in the black beans along with their liquid, stirring well to integrate the mix. Simmer uncovered for about 5 minutes.

Next, incorporate the rinsed long-grain rice and vegetable broth, ensuring the liquid covers the rice by about an inch. Bring the mixture to a lively boil over high heat.

Once boiling, reduce the heat to low, cover the pot snugly with a lid, and let it simmer for 15-20 minutes.

Remove the pot from heat and allow it to sit, covered, for another 5 minutes. Fluff the rice and beans gently with a fork.

Serve the black beans and rice warm, garnished with freshly chopped cilantro and a squeeze of lime juice.