Over low heat, caramelize the onions for at least 45 minutes. The longer, the better.

Add the ground beef and cook until lightly browned.

Add the garlic, tomato purée, chili powder, salt, pepper, brown sugar, ketchup, water, Serrano peppers, and hot sauce. Cook down for 10-15 minutes at a bubbling simmer until consistency is thick.

Serve with toasted hamburger buns.