Tri tip works great!! Don't trim all of the fat off but most of it. Brine it using your favorite recipe. After 10 days remove it from the brine rinse thoroughly sprinkle both sides with pickling spice and vacuum pack it. Place it in a sous vide bath for 12 hours @135°. After 12 hours pull from the water remove from bag. At this point you can slice (against the grain) and enjoy or you can put a sear on it in a cast iron pan, broiler or Weber. I like to mix a couple table spoons of honey with a tablespoon of good quality Dijon mustard and glaze the roast before I sear it!