Place the tenderloin in a slow cooker. Add 1/2 cup beef stock.
Mix 2 tablespoons of brown sugar with the crushed red pepper. Pat onto the tenderloin.
Cook on low for 6 to 8 hours.
While the pork is cooking: mix the soy sauce, rice wine vinegar, 1/4 cup oil, the remaining beef stock, 1 tablespoon of brown sugar and mix until the sugar is dissolved. Let sit until the pork is cooked.
Remove the tenderloin from the slow cooker and cut it into 2″ thick slices. Pull the pork apart using forks or your fingers.
Heat the remaining olive oil in a large skillet over medium-high heat. Add the pulled pork. Brown the meat without stirring, 3 to 5 minutes.
Add the sauce to the pork and stir until it is well blended.