The Tri Tip is  part of the bottom sirloin.  It is a fairly inexpesive cut of meat and is very good.  I made this one as follows: Marinade overnight or as long as you can.  I used a teriyaki sauce, worsteshire sauce, Fresh Garlic, a little salt, fresh pepper and soy sauce. I then made a rub as follows: 1 tbs Kosher salt 1 tbs Black Pepper 2 tsp Garlic Powder 2 tsp Onion Powder 2 tsp Chili Powder or Ancho  Chili (pref) hot pepper to taste (about 1/2-1 tsp for me). Dry Tri Tip after marinade and put on rub. Sear on Big Green Egg at 650F or so for 3-4 min per side. Take off grill and wrap in foil. Get Big Green Egg down to ~350F.  Unfoil the Tri Tip and cook until about 125-130.  Wrap for a few min and then slice across the grain. That was it.  It was really juicy and tasty.  Can't beat the price either. Cheers....JerryD