Some guy at the Cosco meat counter gave me this tip so I thought i would pass it along..
Take your preseasoned Costco Tri Tip..
* Put it in a vacuum-sealed bag with some butter slices (i did ~4 1/4" slices of butter on each side).
* Sous vide for a few hours at 130-135 degrees (I had mine in for about 3.5 hours).
* Remove it from the Sue Vide, pat it dry, add salt and pepper to both sides, and let it rest for 15 minutes.
* Crank the grill up while it's resting (i used a Traeger so 450 was the max it would go)
* Grill for about 8 minutes per side.
* Take it off the grill when it has some good color/sear and let it rest again for 15 minutes.
It was probably the least amount of effort I've put into any grilled meat in a long time, But the people we had over for dinner raved about it... and i have to admit that it was a good tri-tip (if there is such a thing 😃 )