This recipe was shamelessly copied off the Internet unfortunately I can't find it again so I can't give credit to the author. I will say that once we started using this recipe we gave up on the other ones. The brown sugar sweetens the meat just a bit which is balanced by the other flavors.
3 Tbs olive oil
2 Tbs Dijon mustard
1/4 cup bourbon (should be sampled first to ensure it is of an acceptable quality to be used in the marinade)
1/3 cup reduced sodium soy sauce
2 Tbs red wine vinegar
1 Tbs Worcestershire sauce
1/4 cup light brown sugar
2 Tbs red onion
1 Tbs garlic
1 Tbs kosher salt
2 tsp black pepper
Put all the ingredients in a blender and liquefy. Puncture the beef all over with a fork. I put the tri tip in a gallon freezer bag for less clean up. Marinate for at least 4 hours however overnight is better. Cook on the grill on medium heat until the internal temperature is around 130° F. As with any tri tip let stand covered for at least 15 minutes after cooking. Slice in thin strips across the grain.