Using an immersion circulator, preheat a water bath to 135°F.
Season each tri-tip with salt and pepper. To a vacuum seal bag add venison, about 1 tablespoon olive oil, herbs, and garlic. Vacuum and seal.
Cook the venison in the water bath for 2½ hours. Remove from the bath and pat dry with paper towels; lightly season fat side with salt and pepper. Set aside herbs and garlic; discard bag.
Heat a heavy bottom skillet over medium-high flame. Place the tri-tips in the pan, fat side down, and sear until fat renders and tri-tip is deeply browned. Turn tri-tips over and add butter and reserved garlic and herbs. While the flesh side sears, tilt the pan so the butter pools, and using a spoon, baste the tri-tips several times with the seasoned butter. When evenly browned all over, remove from heat and rest for 5 minutes before slicing against the grain and serving.
This sous vide venison tri-tip recipe ensures the lean meat stays tender and juicy while keeping the perfect temperature at medium-rare.