In a Dutch oven, cook ground beef and onion over medium-high heat until beef is no longer pink, 6-8 minutes; crumble meat. Add garlic; cook 1 minute longer. Drain. Add next 5 ingredients; bring to a boil. Add lentils and water. Reduce heat; simmer, covered, until lentils are soft, about 1 hour, stirring often. Add water if mixture seems too dry.