sous vide...or a modified version thereof.
vacuum seal the cooked tri-tip (which I assume you are finishing to a very rare condition) and store in fridge until day of.
let sit out for about an hour and then immerse them in water not more than 120F - weighted if necessary to ensure all surfaces of the bag are in contact with water. Allow several hours for this re-heating to occur - but no worries, because you are controlling the heat the temp will not climb above the setting you have for the water bath.
This way you are not "boiling" them at 212F + ---- you are using a controlled water bath set at the temp you desire the finished meat to achieve and by placing the sealed package of smoked meat in the water bath you will be able to raise to the temp you want. 120+F would be rare, 130+F med rare, etc.
[SIZE=2][B] [SIZE=3][COLOR=Navy][FONT=Comic Sans MS][I][SIZE=3][U]CB[/U]_____________
[/SIZE][/I][/FONT][/COLOR][/SIZE][/B][/SIZE]RED 3-Burner & Urban Grill
Quantum 3-Burner & Urban Grill
Silver & H2O Smokers
Double Chef Smoker
CB940X Charcoal Grill
The Big Easy Oil-less Turkey Fryer
Big Easy Smoker-Roaster-Grill
Outdoor Stove-Top & Smoker
Rambler on-the-go! grill