Heat oil in a large stockpot over medium high heat. Add ground beef and onion, and cook until beef is well browned and crumbled. Drain fat, and transfer beef to a slow cooker. Add cabbage, kidney beans, water, tomato sauce, bouillon, cumin, salt, and pepper. Stir to dissolve bouillon, and cover.
Cook on high setting for 4 hours, or on low setting for 6 to 8 hours. Stir occasionally. Enjoy!