CARAMELIZED Onions: Cook onions in hot oil in skillet on medium-low heat until caramelized, stirring frequently. Stir in steak sauce.
SLAW: COMBINE first 4 ingredients in large bowl. Whisk remaining ingredients in separate bowl until blended. Add to cabbage mixture; toss to coat. Refrigerate until ready to use.
BURGER Patties: Mix ingredients just until blended; shape into 16 (6-oz.) patties (or shape into 1 [6-oz.] patty for trial recipe).
FOR each serving: Grill 1 Burger Patty to desired doneness. Fill 1 bun with 1 Tbsp. Caramelized Onions, 1 Burger Patty, 1/3 cup Slaw, 1 lettuce leaf, 1 egg, 1/4 tsp. each sesame seed and chives, and 1/4 cup won ton strips.