Combine garlic powder, black pepper and kosher salt in a small bowl. Trim tri-tip of excess fat and silver skin. Season roast with rub and place in zip-loc bag, removing excess air.

Adjust sous vide to 135°. When water is at temperature, add roast. Set timer for six hours.

When the roast has been in the sous vide for at least six hours, prepare grill to finish roast.

Remove roast from bag and pat dry with paper towels. Brush with olive oil and grill at high heat to sear outside.

Let roast rest for five minutes, slice and serve.