In a large measuring cup, mix together the ketchup, mustard, Worcestershire, balsamic vinegar, brown sugar and spices; set aside. In a large skillet over high heat, sauté the beef. When it has browned, pour off most of the fat and then add in the onions, garlic, and jalapeño and sauté for 2-3 minutes. Turn the heat down to low, and the sauce and cook for 10 minutes.
Split buns and lightly butter them and place face side down on a hot griddle or large skillet. Allow to toast until lightly golden. Just a little extra goodness and the toasting helps hold the sloppy meat mixture.
Divide the mixture among the buns and serve.