In a small bowl, combine the garlic powder, onion powder, pepper, oregano, and 1/2 tsp Cajun seasoning. Rub mixture over pork and place in slow cooker. Add water and vinegar around the roast. Cover and cook on low for 8 hours. When done, remove and shred.
Meanwhile, combine.Cover and chill until serving.
Place all the ingredients for the remoulade sauce in a blender or food processor and blend until smooth. Cover and refrigerate until serving.
Preheat oven to 350 degrees. Split open rolls and spread with butter. Place on a baking sheet. Bake at 350 for 7-10 minutes until lightly toasted.
When roast is cooked, remove from slow cooker and shred.
Fill toasted buns with pulled pork, lettuce and sliced tomatoes. Drizzle remoulade sauce over top and serve immediately. Serves 6-8.