Heat oil in a large Dutch oven over medium heat. Add the onion and cook until the onion starts to soften
Add the ground beef and garlic. Cook until meat is no longer pink.
Add cumin, chili powders, tomatoes, and beans.
Add the Guinness® and brown sugar, stir
Cover and simmer for at least 1 ½ hours. I usually let it simmer for 2-3 hours.
Top with sour cream, chopped green onions, and shredded cheese (optional)