What can I substitute for hot Korean chili oil in this pork noodle recipe?
You can always just make your own Korean chili oil. For example, here's The Woks of Life formula for chili oil:


  1½ cups oil (ideally a vegetable, peanut, or grapeseed oil…light olive oil is fine, but it has a tendency to set in the fridge)
  5 star anise
  1 cinnamon stick, preferably cassia cinnamon
  2 bay leaves
  3 tablespoons Sichuan peppercorns
  ¾ cup Asian crushed red pepper flakes (Sichuan chili flakes are the best)
  1 – 1½ teaspoons salt (to taste)
  
  Heat the oil, star anise, cinnamon stick, bay leaves, and Sichuan peppercorns in a small saucepan over medium high heat. When the oil starts to bubble slightly, turn the heat down to medium.