Grilling steaks with garlic butter mushroom sauce is straightforward when you follow these steps:

1. Preheat the Grill: Heat your grill to medium-high heat. If using a charcoal grill, make sure the coals are hot and ashy.
2. Season the Steaks: Pat the ribeye steaks dry with paper towels. Season both sides generously with salt and black pepper.
3. Prepare the Garlic Butter Sauce: In a skillet over medium heat, melt 1 tablespoon of butter. Add the sliced mushrooms and sauté until they are golden brown, about 5-7 minutes.
4. Add Garlic: Stir in the minced garlic and cook for an additional 1-2 minutes until fragrant. If using, add soy sauce and mix well. Remove the skillet from heat and set aside.
5. Grill the Steaks: Brush the grill grates with olive oil. Place the steaks on the grill and cook for 4-5 minutes on one side. Flip and grill for another 4-5 minutes for medium-rare, adjusting the time for your preferred doneness.
6. Add Butter: During the last minute of grilling, add the remaining butter on top of the steaks to melt.
7. Serve: Remove the steaks from the grill and let them rest for a few minutes. Top with the garlic butter mushroom sauce and garnish with fresh parsley before serving.

Following these steps will help you create beautiful, flavorful steaks that are sure to impress.