In a large bowl, combine the steak pieces, oil, soy sauce, Worcestershire sauce, and minced garlic. Cover and marinate for at least 8 hours.
Heat the grill to medium-high heat, approximately 400 degrees F. Lay out 4 large pieces of aluminum foil on your counter or work surface.
Uncover the marinaded steak and add the mushrooms, tossing to coat in the liquid.
Divide the mixture evenly between the 4 pieces of aluminum foil, reserving the liquid at the bottom of the bowl.
Add 1 tbsp of the reserved marinade to each foil packet, and sprinkle each foil packet with ½ tsp steak seasoning.
Fold the foil packets by bringing 2 sides together and folding them over, then closing the ends.
Grill the packets for 15-20 minutes, until the steak is cooked per your preference. For my grill, it took 18 minutes for the steak to reach medium-rare consistency. Remove the packets from the grill, and allow them to rest for at least 5 minutes.
Open the packets, garnish with fresh thyme, and serve!