Grilled Beef Tri Tip | The BBQ Pro Shop Test Kitchen 

If i might offer a suggestion: Marinade that tri-tip in a proprietary blend of salt, harissa (get it from mccormick spices in powder form), beef stock, and a dash of cider vinegar overnight. Cook it at 225 in the oven or on the smoker (preferably) with post oak until it hits 130 degrees inside. If cooking in the oven, sear it quick in a cast iron pan to get color on the outside before you let it cool and throw it in. Sweet, spicy, with a solid kick, you won't be disappointed. I also make sure no matter how i'm cooking it that i set it on top of a rack to ensure even heating, and usually prop up the tail end with a block of whatever wood you're cooking on to keep the tail end from hitting the rack and drying out.