Mix tequila, sesame oil, Dijon mustard, balsamic vinegar, garlic, salt, and pepper in a small bowl and place in a large zip-top bag with tri-tip. Marinate at least two hours before desired grilling time.
Grilling Method: Pre-heat gas grill to 400 degrees F. Place meat on grill top-side down for 3-4 minutes for nice grill marks. Flip over and reduce heat slightly - close lid, if possible. To be prepared for flare-ups, keep an open beer by the grill and use as a 'fire extinguisher.' If no flare-ups occur, then enjoy the beer yourself! Cook for 20-25 minutes or until meat thermometer inserted in center reads 135-140 degrees F. for medium. Slice thin and enjoy with a fine Cabernet Sauvignon.