I got this recipe from a recent issue of Bon Appetit. Tri tip is marinated in red wine, soy sauce and garlic. The meat is roasted with mushrooms and green onions. The recipe called for baby portobello mushrooms, but I used cremini mushrooms. Cremini is the same variety as portobello, just smaller. I chose to marinate the mushrooms too. The chinese mustard sauce that accompanies this dish is a blend of equal amounts of honey, dry mustard and water with a pinch of salt. It's spicy, so use it sparingly! I served this with basmati rice on the side.