I had my tri-tip with truffle mac and cheese (http://www.instructables.com/id/White-Truffle-MacnCheese-with-Crispy-Topping/) and braised swiss chard with red onions. And leftover steak sammies of course!
If you don't have a sous vide machine, skip to Step 5 for cooking instructions.
Preheat your immersion circulator to 135F for perfectly medium rare meat. Once it's hot, drop in your tri-tip and set your timer for 90 minutes (for a two pound roast). The beauty of this cooking method is that the meat will never overcook. However, I would not recommend cooking the roast for more than three hours because the connective tissue in the meat begins to break down and become a bit mushy.