How to Make It
Heat the oil in a large saucepan over medium heat. Add the onion, garlic, and red pepper. Sauté until fragrant, about 3 minutes.
Add the ground beef and brown, about 5 minutes.
Stir in the tomato paste, chili powder, cumin, salt, black pepper, and cinnamon. Simmer, stirring occasionally, until thickened slightly, about 12 minutes.
Spoon onto the buns. Sprinkle each with the Cheddar and top with a dollop of the sour cream.