In a 3 quart sauce pan, over medium heat, add the olive oil. Add the diced onions and cook until the onions are transparent and begin to tenderize, about 6-8 minutes. Add the garlic and cook for 1 more minute. To the onion/garlic mixture, add the tomato paste, salt, mustard, cloves, allspice, cinnamon, and red pepper flakes to the pan. Stir until the tomato paste is combined and the spices are fragrant, about 45 seconds to 1 minute. Add the pureed tomatoes, brown sugar, apple cider vinegar and stir to combine.