Heat a Dutch oven over medium-high heat. Cook and stir beef, onion, salt, and pepper in the hot skillet until browned and crumbly, 5 to 7 minutes; drain and discard grease. Add bell peppers; cook and stir until peppers are softened, about 5 minutes.

Mix chicken stock, salsa, tomato sauce, canned tomatoes, and black beans into ground beef mixture; bring to a boil. Reduce heat to medium and simmer for 45 minutes. Add rice and corn and simmer for 30 minutes more. Season soup with salt and pepper.