In a large skillet, heat the oil over medium-high heat. Add the onion and bell pepper and cook until softened, 5 to 7 minutes. Add the ground beef and break apart into small pieces with a wooden spoon. Cook until no longer pink, 6 to 8 minutes. Add the garlic and cook 1 more minute.
Drain the beef mixture then transfer it to a slow cooker with the chili powder, cumin, and oregano. Stir in the tomatoes (with their juices), tomato sauce, kidney beans, beef broth, chipotle chile, adobo sauce, salt, and black pepper. Cover and cook on high for 4 hours or low for 6 hours. Reduce the heat to warm and serve out of the slow cooker.
Serve bowls of chili with sour cream, cheese, sliced jalapeños, and corn tortilla chips.
