Combine rice and chicken stock in a medium sauce pan. Cook the rice according to the package directions.
Meanwhile, heat the oil in a saucepan over medium-high heat. Add the onion, bell pepper, cumin, oregano, and garlic. Cook, stirring occasionally, until softened, 5 to 7 minutes.
Add beans and stir well to combine. Reduce heat and simmer for 10 – 15 minutes.
Add the vinegar. Smash some of the beans with the back of a fork to thicken. Serve over the rice.
