Remove from refrigerator 30 minutes before grilling. Pre-heat grill on high heat.
Place tri-tip roast on heated grill, saving any left-over marinade in dish, searing both sides for 4 minutes.
Be sure to watch carefully to avoid grill flame ups.
Turn grill down to low-medium heat and grill meat rotating 1 time for additional 15 minutes (about 7.5 minutes each side) for medium rare.
For more well-done grill additional minutes.
Remove from grill and let rest covered for 7-10 minutes.
While roast is resting place saved marinade in small saucepan on low-medium heat on stove. Bring to a simmer and cook for 8-10 minutes.
Slice Tri-tip thin with the grain of the meat, drizzle with balsamic sauce.