Heat a large skillet over medium-high heat. Add oil and meat to the pan. Spread the meat around the pan and begin to break it up. Combine brown sugar and steak seasoning. Add sugar and spice mixture to the skillet and combine.
When the meat has browned, add onion and red peppers to the skillet. Reduce heat to medium and cook onions, peppers, red wine vinegar and Worcestershire sauce with meat for 5 minutes. Add tomato sauce and paste to pan. Stir to combine.
Reduce heat to simmer and cook Sloppy Joe mixture 5 minutes longer. Using a large spoon or ice cream scoop, pile sloppy meat onto toasted, buttered bun bottoms and cover with bun tops.