Stir together hoisin, garlic, sesame oil, soy sauce and cornstarch; set aside.
Place coleslaw mix and carrots into slow cooker. Cut the pork into 1/8-inch-thick slices, then cut each slice in half lengthwise; sprinkle on top of cabbage mixture in slow cooker. Drizzle with 1/4 cup of hoisin sauce mixture. Cover and cook on HIGH for 4 hours or LOW for 6 hours.
Remove cover; stir in remaining 1/2 cup hoisin sauce mixture.
Heat tortillas according to package directions. Place 1/2 cup pork mixture in center of each tortilla, top with scallion strips, if desired, and roll up.