Preheat the broiler. In a bowl, combine the hoisin sauce, soy sauce, vinegar and sugar. Pour half of the mixture into a second bowl and stir in the cornstarch.
Thread the pork and mushrooms onto 8 skewers. Rub with 1 tablespoon oil and place on a baking sheet. Cook, turning once, for 5 minutes. Brush with the hoisin mixture without cornstarch. Cook, turning once, for 4 minutes.
In a skillet, heat the remaining 1 1/2 teaspoons oil over medium-high heat. Add the coleslaw mix and cook for 2 minutes. Stir in the hoisin-cornstarch mixture and cook, stirring, for 1 minute. Serve with the kebabs and tortillas.