Mix the garlic, ginger, Umami 33, soy sauce, and pepper to make a marinade. Put the steak cubes into the marinade and let sit for one hour or longer.
Prepare a grill for direct heat cooking. Thread the meat and mushrooms onto the skewers. Grill for ~8 minutes or to desired doneness, brushing the meat with the leftover marinade. Remove from the grill and serve hot.
Makes 4 servings