1In small bowl, mix all slaw ingredients; set aside.
2In large skillet, heat oil over medium-high heat. Cook mushrooms in oil 3 to 5 minutes, stirring occasionally, until they begin to brown. Add onion; cook 2 to 3 minutes longer. Stir in grill seasoning and sweet-and-sour sauce; cook 1 minute or until hot.
3To serve, spoon mushroom mixture into buns; top with spicy cabbage slaw and green onions.