So they had tri-tips on sale at Vons. Got one. It was pretty thick and the butcher offered to split ( butterfly it). I never did one like that before, so I told him to go for it. Now I got this big slab of butterflied beef, and I'm thinking...hmmm, what can I cram in there? Got some porcini and portabella mushrooms, crumbled bleu cheese, and some fresh basil. Mixed that all up and jammed it into the roast. Rubbed a little salt and lemon pepper on the outside, tied with string, and put in on foil on the grill. Indirect heat at about 300 degrees for about 30 minutes (2.5 lbs of meat). HOLY COW!! That was sooooo good!. If I do it again I might sautee the shrooms with a little olive oil and red wine before putting in the roast with the cheese. Experimentation occasionally works out!