Lay out two large pieces of foil on the counter. Place one rack of ribs on each piece.
Drizzle liquid smoke on ribs and rub into the meat with your hands.
Lightly sprinkle rub on both sides of ribs. Be careful not to put too much-the salt will concentrate during the cooking process and they will become very salty if there is too much rub.
Wrap the foil around the ribs tightly and place on a baking sheet. You should be able to fit two racks on one baking sheet.
Place in the oven for 2 hours for Baby Back and 3-4 hours for St. Louis style.
At the end of the cooking time the ribs should be falling apart. At that point brush on your BBQ sauce of choice. Do not wrap the ribs back up. Leave the foil open and place back in the oven for an additional 25-30 minutes or until the sauce becomes sticky.
Notes:
* The St. Louis style will feed more because they have more meat so consider that when buying.
* If you do not want to use a rub you can lightly salt and pepper instead and use the BBQ sauce at the end as the main flavoring.
* A little liquid smoke goes a long way so be careful when applying. I like mesquite, but you can use hickory or applewood.