Preheat an indoor or outdoor grill to medium heat. Combine the vinegar, sugar, oil, salt and pepper in a large bowl. Add the cabbage, carrot, celery, green onion and apple and toss to combine. Grill wieners until nicely coloured and heated through. Place a wiener in each hot dog bun. Top each with 1 tsp. of the mustard. Mound some coleslaw on top of each wiener and serve.