In a large pot, heat up olive oil on medium heat. Add the onion and garlic and sauté until the onion is translucent. Add all of the spices, salt and pepper, and cocoa powder and stir to combine. Cook for 5 minutes, allowing the spices to toast up and release their aroma. Pour the water in the pan and use a wooden spoon to loosen the spices from the bottom of the pan. Add the meat to the pan and stir to combine. Sauté until the meat is browned through. Add the tomato sauce and rice vinegar, stir to combine. Reduce heat to low, cover and simmer the chili for 1-1/2 hours, stirring every 5-10 minutes. (If you want to use a slow cooker, pour the complete mixture into your slow cooker after adding the tomato sauce and vinegar and set it on high for 3 hours.)
Start with a hot cast-iron skillet. Combine ground beef and ground sirloin and form into 6 oz. burger patties (Make an indentation in the middle of the patty with your thumb to give it room to expand without falling apart.) Sprinkle salt and pepper on top. Place the patty in the skillet to cook. After the patty crisps on the outside, remove from heat.
Place the patty on the bottom bun and top with chili, shredded cheddar cheese and sour cream. Add other favorite toppings and your top bun and ENJOY!