In a large skillet over medium-high heat, cook ground sirloin until browned and crumbly, about 5 to 7 minutes. Drain excess grease.
Add green bell pepper and diced onion to the skillet; cook and stir until onion is soft and translucent, around 5 minutes.
Mix in diced tomatoes, tomato sauce, chicken broth, thyme, and sage. Season with salt and pepper. Cover and simmer until peppers are tender, approximately 30 to 45 minutes.
In a separate saucepan, bring water and rice to a boil. Reduce heat to medium-low, cover, and simmer until rice is tender and water is absorbed, about 20 to 25 minutes.
Stir the cooked rice into the soup, heat through, and serve.
Notes
For a heartier version, consider adding cooked beans or lentils to the soup for extra protein and fiber.