Coat a Dutch oven with cooking spray; place over medium-high heat until hot. Add pepper, onion, and garlic; cook, stirring constantly, 3 to 5 minutes or until tender. Add ground round, and cook until beef is browned, stirring until it crumbles. Drain well.
Stir Mexican seasoning into beef mixture; cook 1 minute. Add tomatoes and next 4 ingredients, stirring well. Bring to a boil. Cover, reduce heat, and simmer 20 minutes, stirring occasionally.
Ladle chili evenly into 5 individual serving bowls. Top servings evenly with sour cream.