I wrote this up on another forum for someone asking for first time cooking advice.
context was a cook on the large BGE, but will adapt to anything that can smoke indirect and sear.
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There are lots of way to smoke, sear, roast tri tip. Here is my technique, and I keep evolving it.
I smoke until the tri-tip reaches about 120 to 125F internal temp, pull the tri tip and put it into a warm serving dish covered in foil. It doesn't really need to rest, but I wrap it in foil, mostly to just keep it warm while the coals are getting hot.
I get the coals flaming hot, almost like cooking over live fire.
(BGE specific)
I use the drop spider from CGS and a 14 1/2 inch heavy duty grid which gets the cooking surface even closer to the coals.
As far as the actual reverse sear. Once the coals are HOT, I put the TT back on and flip it often. like every 30 to 45 seconds. I don't walk away from the fire once the reverse sear starts.
edit: here's a pic of how hot I have the coals for the reverse sear:
Since the TT was already in a serving dish, and already had foil over it, I keep these warm by having a bit of it overhang the egg.
The end-game of searing comes with experience and internal temp of an instant read. When it "feels" close I'll pull it off the coals set it in the serving dish and let it just sit for a minute. Then I temp it with an instant read. 128F to 130F is my target for the thick section. If the thicker section is still wobbly and reading cooler I'll hold the tri tip by the narrow point with tongs and only sear the wider and thicker part.
When its done Ill cover it in foil, bring it in and let it rest a few minutes.
As far as "Done-ness" I've not over cooked a TT since I started reverse searing, but I have under cooked a couple. I like my beef rare, but I've found Tri tip is more tender when on the high side of medium rare.
The last and most important part is carving the TT. If it is cut with the grain it is chewy, so finding the seam, making that the first cut and then cutting across the grain is needed to ensure a tender bite.
