1. In a small bowl, mix garlic powder, salt, pepper, and parsley together; rub all over and into meat. Let stand at least 1 hour at room temperature and up to several hours if chilled (bring to room temperature before grilling).
2. Meanwhile, prepare a charcoal or gas grill for indirect medium-high heat and add chips, if using, to grill (if it’s gas, put them in a small disposable aluminum pan and set it on the lit burner; if charcoal, sprinkle them on the coals). Set tri-tip over direct heat, fat side up, and sear until nicely browned (close lid on gas grill), 3 to 5 minutes; turn over and sear other side.
3. Move tri-tip over indirect-heat area and grill, turning every 10 minutes or so, until an instant-read thermometer inserted into thickest part registers 125° to 130°, 25 to 35 minutes.
4. Transfer tri-tip to a cutting board and let rest at least 15 minutes. Slice meat across the grain as thin or as thick as you like.
Quick tip: Find red oak chips online from Susy Q's Brand (susieqbrand.com).
Note: Nutritional analysis is per serving.