Remove the membrane from the back of the ribs as it can be tough and chewy.
Rub the ribs with molasses then the barbecue rub. Adjust the barbecue rub so the ribs are fully coated with the seasoning.
Let them sit uncovered, for 4-8 hours (or overnight) in the fridge.
Preheat a sous vide water bath to 145F degrees.
Place them in a vacuum seal bag and add the liquid smoke.
Seal the bag and cook for 36 hours in the water bath.
Remove from the water bath, pat dry, and place on a foil lined baking sheet.
Preheat an oven (or grill) to 300F degrees.
Brush the ribs with BBQ sauce and bake for 45 minutes, basting with extra sauce every 15 minutes.
Remove, slice and serve with extra sauce.
You may need to cut the rack in half to fit it in the sous vide bag.
The ribs should be cooked in a flat layer. If you have trouble fitting the two pieces in the same sealable bag, you can seal the ribs in two separate bags.
Use a lid, foil, or plastic wrap over the container so the water does not evaporate during the long cook. Check it periodically and add more water to ensure it doesn't go below the water level (this will cause your sous vide to turn off and could ruin your food).
If the bag starts to float, just open it, release the air and seal it again. You can also weigh the bag down with something heavy like asous vide sinker weight.
Always make sure to remove as much air as possible from the bag - this helps prevent floating as well as helping to keep harmful bacteria out of the bag.