Slow cooker: Brown the beef with the onion, peppers and garlic, then drain. Add everything except the rice to the slow cooker. Cook on low for 4–6 hours or on high for 2–3 hours. Stir in the cooked rice during the last 15 minutes.
Keep the rice from getting mushy: Rice keeps absorbing broth as it sits. For leftovers, store the rice and soup separately if you can, or add a splash of broth when reheating.
Freezing: Freeze the soup without the rice for up to 3 months. Thaw overnight in the fridge, reheat on the stove, and stir in freshly cooked rice.