In another bowl whisk together the hoisin sauce with garlic, soy sauce, rice vinegar, sesame oil, ginger and black pepper to taste (if using).
Pour HALF of the hoisin sauce mixture over the pork strips; mix to coat, and let stand for about 30 minutes.
Heat about 1 tablespoon vegetable oil in a wok or large skillet over medium-high heat.
Add in the pork mixture and saute for about 2-3 minutes, or until the pork is done; remove to a plate or bowl.
Heat another 1 tablespoon oil (or more if desired) in the wok or skillet and saute the dried chili flakes with spinach leaves, water chestnuts, carrots (or broccoli slaw if using) and green onions for about 3 minutes or until the spinach is wilted.
Stir in the cooked noodles with the cooked pork, along with any drippings from the plate or bowl and the remaining half of the hoisin sauce mixture; cook stirring constantly for about 2 minutes or until the mixture is completely heated through.
Add in more soy sauce and season with more black pepper if desired.