
Whisk all of the tri tip marinade ingredients together in a large bowl.
Place the tri tip roast into a large baggie and pour in the marinade. Alternatively, you can use a large bowl. Massage the marinade into the meat and seal (or cover). Refrigerate and marinate the tri tip for at least 8 hours, or overnight. (You can marinate for 1 hour and still get good flavor penetration).
Remove the tri tip from the fridge and bring to room temperature, about 30 minutes.
Heat oven to 425 degrees F.
Heat 2 tablespoons olive oil in a large cast iron pan or skillet to medium-high heat. Remove the tri tip from the marinade. Keep the marinade for a sauce later, or discard it.
Sear the tri tip roast 4-5 minutes per side to achieve a nice crust. Transfer the tri tip to a rack covered baking sheet, or use a roasting pan with a rack.
Transfer to the oven and bake for 20-30 minutes (10-15 minutes per pound) to your preferred doneness. You'll want 125-130 degrees F internal temperature when measured with a meat thermometer for rare, or 130-140 degrees F for medium-rare.
Rest for 10 minutes to redistribute the juices, covered, then slice against the grain and serve.