Place onion in a 1-1/2-quart slow cooker. If necessary, cut beef to fit into cooker; add to cooker. Sprinkle with salt, black pepper, and garlic. Combine cranberry sauce and chipotle peppers. Pour over all.
Cover and cook on low-heat setting for 6 to 8 hours or on high-heat setting for 3 to 4 hours. If no heat setting is available, cook for 4-1/2 to 5-1/2 hours.
To serve, cook rice according to package directions, except omit salt and butter. Serve beef mixture with rice. If desired, garnish with jalapeno peppers. Makes 2 servings.