In a medium size, pot add the shallots and cook until soft, about 5 minutes.
Pour in the bourbon and cook until reduced by almost half.
Add the ketchup, vinegar, sugar, cola and soy sauce and stir.
Simmer on low for about 20 minutes and then transfer to a blender.
Blend on low just to break down any shallot pieces there might still be.
Transfer to a jar.
Preheat your grill to high.
Rub the tri tip with the mustard and then sprinkle with the bbq rub.
Place the tri tip onto the hottest part of the grill and sear for 5 minutes.
Turn the tri tip over and repeat.
move the tri tip slightly away from the direct heat and cook for another 20 minutes turning over periodically.
With about five minutes to go, start brushing the meat with the bbq sauce on both sides. Do this a few times.
Once the meat is ready, transfer to a plate and cover with aluminum foil. let rest for 10 minutes.
Slice the tri tip across the grain into thin slices and serve with extra sauce on the side.