Mix salt and sugar together in a small bowl. Sprinkle all over ribs. Coat with red pepper flakes, five-spice powder, and black pepper. Slide ribs into a large vacuum-seal bag; pour in liquid smoke. Seal.
Immerse bag in a heat-proof container of water with a sous vide cooker. Set temperature to 140 degrees F (60 degrees C); cook for 8 hours.
Preheat oven to 450 degrees F (230 degrees C). Set oven rack about 6 inches from the heat source and turn on the broiler. Place a wire rack on top of a baking sheet.
Pull ribs out of the bag; spread onto the prepared baking sheet and brush with barbeque sauce.
Bake in the preheated oven until bubbly, 4 to 5 minutes. Flip and continue baking until other side bubbles, 2 to 3 minutes more.
if you're lazy like me, just throw the pork in the bag, dump the salt and sugar in, and spread it around the best you can. It probably doesn't get distributed quite as well, but I've rarely had a problem.
Feel free to use your favorite barbeque sauce. The Bourbon Whiskey BBQ Sauce recipe (on Allrecipes) is great.
Per Serving: 278 calories;17.4 g fat;
14.9 g carbohydrates;
14.5 g protein;
60 mg cholesterol;
1836 mg sodium.