My family enjoys tri-tip frequently, but to flavor it up a bit, I created this marinade. It is super easy, and really tasty!
In a Ziploc bag, combine equal parts Soy Sauce and Worcestershire Sauce (about 1/2 to 3/4 cup each). Coat roast with sauce then sprinkle approx. 1 tsp. each garlic powder and onion powder. Sprinkle on 1/2 tsp. of Rosemary (or Rosemary/herb blend).
Seal bag and put in refrigerator. Turn over every few hours, for even flavor.
Grill tri-tip and enjoy!