Combine chili sauce, ketchup, vinegar, sugar and mustard in a small saucepan. Bring to a boil over medium-low heat. Reduce heat to low and simmer for one minute. Cover and set aside.
Combine sugar, garlic salt and cayenne in small cup.
Heat gas or charcoal grill to medium-hot.
Combine pork, mustard and 1-1/2 teaspoons of the Seasoning Mix. Shape into 6 patties about 3/4 inch thick. Place on a cookie sheet lined with plastic wrap. Sprinkle remaining Seasoning Mix over both sides of patties. With the back of a spoon press a 1/2-inch indentation in center of each burger for even grilling.
Using a long-handled brush, season rack with vegetable oil.
Grill patties 4 minutes. Turn; grill 4 minutes longer or until they register 160°F on an instant-read thermometer.
Spoon 2 tablespoons coleslaw on bottom piece of each muffin. Top each with a burger, a generous tablespoon of BBQ Sauce, and muffin top. Serve extra sauce on the side.