Preheat outdoor grill to medium heat. Rinse roast with cold water and pat completely dry with paper towels. For the dry rub, in a small bowl, combine ingredients for dry rub. Season tri-tip with kosher salt. Rub a generous amount of dry rub into both sides of meat. Let set for 10 to15 minutes. Repeat rub 2 or 3 times until all seasoning is used.
While meat is resting between rubs, prepare BBQ sauce. In a saucepan over medium heat, combine all ingredients for BBQ sauce. Bring to a boil, lower heat and simmer for 15 minutes. Set aside about half the sauce for serving, use half as a mop while grilling. Oil grill or spray with cooking spray. Grill meat about 20 minutes total for medium-rare, turning and mopping with BBQ sauce every 5 minutes. Transfer meat to a cutting board. Tent with foil, let stand 10 minutes. Cut diagonally across the grain. Serve with extra sauce.
Cooks Note: If cooking on a grill pan, sear meat 5 minutes on both sides then finish in a preheated oven at 400 degrees F for 10 to 15 minut