Prepare rice according to package instructions. Meanwhile, heat oil in a large saucepan over medium. Add onion, garlic, and bell pepper. Cook, stirring occasionally, until onion is softened, 8 to 10 minutes.
Add beans, broth, vinegar, and oregano. Cook, mashing some beans with the back of a spoon, until slightly thickened, 6 to 8 minutes. Season with salt and pepper. Fluff rice with a fork. Serve beans over rice, with garnishes, if desired.
If you like, serve this protein-rich vegetarian dish with brown rice to boost the health factor even more. It's also delicious with chips or tortillas alongside. Canned beans are a great time-saver to stock in the pantry, but they're often high in sodium, so rinse them in a colander before using.