Flip the ribs over and apply the mustard/oil and seasoning to the meaty side.
Place the ribs in the fridge overnight if you are making them ahead of time, otherwise, they are ready for the smoker.
Setup your smoker for cooking at 225°F (107°C) using indirect heat. if your smoker uses a water pan, fill it up.
Once the smoker is ready, place the rack(s) on the grate and leave them alone for about 3 hours.
Make a mop using 1 stick of melted butter and 2 TBS of Jeff’s Texas style rub. Mix together well and apply liberally to the ribs about every 30 minutes during the last 2-3 hours of the cook time.
When the ribs reach 195°F (91°C) as measured right between the bones, they are finished cooking. You may also see the bones protruding due to the meat shrinking up along the sides and when lifted with tongs, the rack of ribs will bend almost in half.
Wrap in foil and keep them warm for an hour or two if you’re not eating right away.
When it’s almost time to eat, lay them on the cutting board and slice into individual ribs right between the bones.