Heat the olive oil in a large skillet on the stove over medium-high heat. Add the onion to the pan and cook until it starts to soften, about 2 minutes.
1 tablespoon olive oil, 1 medium yellow onion
Add the ground beef to the pan and cook until browned, crumbling with a spoon or spatula. Drain off excess grease as needed.
2 pounds lean ground beef
Add the garlic, tomato paste, chili powder, cumin, oregano, salt, pepper to the pan and cook, stirring, for 1 minute. Then stir in the beef broth and scrape up any browned bits from the bottom of the pan. Transfer the contents of the skillet to the slow cooker.
4 cloves garlic, 6 ounce can tomato paste, 1 ½ tablespoons chili powder, 1 tablespoon ground cumin, 1 ½ teaspoons dried oregano, ¾ teaspoon salt, ¼ teaspoon black pepper, 1 ¼ cups low sodium beef broth
Add the crushed or diced tomatoes and brown sugar to the slow cooker. Stir.
28 ounce can fire roasted crushed tomatoes, 1 ½ tablespoons brown sugar
Gently stir in the kidney beans, black beans and pinto beans.
15 ounce can red kidney beans, 15 ounce can black beans, 15 ounce can pinto beans
Cover and cook on low for 6 to 8 hours or on high for 3 to 4 hours.
Serve chili with toppings as desired.