Heat a cast iron oven over medium heat and add oil.
Add ground beef and allow it to brown before moving, then start chopping it up with a wooden spoon. Cook until brown for another 5 mins. Drain liquid and set aside.
In the same pot. Add butter, once melted, quickly add the onion, pepper and garlic and stir occasionally until translucent.
Add the tomato paste and stir. Then add, brown sugar, mustard, Worcestershire, liquid smoke, paprika.
Stir for 30 seconds and then add the ketchup and vinegar.
Allow to cook for 5 minutes, season to taste and serve or cook. The longer it cooks the better the flavor.
Scoop onto buns that have been brushed with butter.