Coat a large saucepan with cooking spray; place over medium-high heat until hot. Add meat, onion, and garlic, and cook until the meat is browned, stirring to crumble. Drain well, and return mixture to pan. Add beans and the next 8 ingredients (beans through pepper); stir well. Cover, reduce heat, and simmer for 20 minutes. Serve with sour cream. Garnish with sliced green onions, if desired.