Per Tri-tip (trimmed, no fat):
3 Large Garlic Cloves - Minced fine.
1 Tbl Kosher Salt
2 tsp Coarse Black Pepper
1 tsp Dried Thyme crushed leaves.
Mix all in a bowl and rub all around the Tri-tip the night before. Smoke at 235 - 250 for about 3 hours. Pull at your desired temp for doneness. I use straight apple wood when smoking. Everyone I have catered for loves this and wants to know the secret.
Grilling: Marinate over night in a non-reactive bowl with one whole bottle of Basque meat marinade. Add one or two lemons (juiced). Grill over high heat for about 10-15 minutes on both sides.
I have never grilled over oak. Just charcoal. Either way, it comes out great.
Tri-tip is tricky. You may not get it right the first few times, but once you do, you are going to love it.