Combine garlic, jalapeno, lime juice, water and salt and blend until well mixed. Marinate tri-tip overnight before removing to de-chill.
Prepare 500F oven. Remove roast from marinade and reserve marinade. Dubiously: oil tri-tip before placing in a roasting pan, fat-side up, and including up to 1/2" of marinade into the roasting pan. Cook for 20-40 minutes, as necessary.
Sauce: Sautee mushrooms, onion and garlic in olive oil until softened. Add wine to a volume sufficient to allow mushrooms to absorb most fluid.