Place steaks in a shallow baking dish and season with salt and freshly ground black pepper.
In a small bowl, combine garlic, gf soy sauce, sherry, honey and vegetable oil. Pour liquid mixture over steaks. Let sit at room temperature for 15 minutes.
Meanwhile, prepare a grill. Grill steaks for 5 minute per side, (brush steaks with marinade half way through), or until desired level of doneness. Remove steaks from grill and tent with foil to keep warm. Let rest for 5 minutes before serving.
While steaks are cooking, heat olive oil in a medium skillet over medium-high heat. Add shallots and garlic; sauté for 3-4 minutes or until tender. Add mushrooms; sauté for 4 minutes or until tender. Season with salt and freshly ground black pepper.
To serve, place steaks on individual dinner plates and top with mushroom mixture.