I've prepared tri-tip in this way before without cooking it sous-vide and it was perfectly delicious, so if you don't have an immersion circulator, I've included cooking instruction using a large cast-iron skillet instead.
Step 1: Preparing the rub
Simply measure into a bowl, and mix:
1 tsp paprika
1 tsp garlic powder
1 tsp black pepper
1.5 tsp sea salt (I prefer coarse ground, especially if the meat is going to be grilled)
2 tsp ground coffee
I made this amount of rub anticipating using it all to season a tri-tip that was a little under two pounds.
Step 2: Preparing the Meat for it's Hot Tub Bath
I like to trim all of the fat that I can off the outside of the roast. This is an especially important step since I'm preparing my meat sous vide, so the fat won't render the same way it would in a pan.
Once your meat is trimmed, pat it dry with a paper towel and apply the rub using your hands. Cover the entire roast using all of the rub, pressing it into the meat.
Step 3: Marinate
Step 4: Give that Sucker a Bath
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.
Step 5: Sear the Roast
Once your skillet is very hot, pour in a tablespoon of oil (I prefer evoo) and immediately put the tri tip in the hot pan. Let it sear for two minutes or until it is nice and brown on each side. You should hear a lot of sizzling and crackling. If you don't your pan isn't hot enough. The meat is already cooked before it goes in the pan, so this step is just to ensure a nice crust and to bring out some more of the flavor in the rub.
NOTE: If you aren't cooking sous vide, simply place your raw roast (marinated) in the hot pan with oil and sear on one side for four minutes. Flip the roast over and put it in an oven pre-heated to 375F and cook until it reaches an internal temp of 135F with a meat thermometer. This can take anywhere from 20-30 minutes. Insert the meat thermometer at the thickest part of the roast for accurate temp. The rest of the steps are the same.
Step 6: Let the Meat Rest, Slice, and Serve
Make sure your knife is very sharp. Slice the meat against the grain into thin strips and serve immediately.