Pat steaks dry then generously season both sides of steaks with salt and pepper. Heat grill to medium and add steaks. Cook to preferred doneness, medium well approximately 3-4 minutes on each side.
When steaks are done and while they are resting, melt butter in a medium sauté pan on medium high. Add garlic and stir cooking for about 30 seconds.
Add mushrooms and continue stirring to coat in butter. Add balsamic vinegar, kosher salt, and oregano and continue cooking until liquids have mostly reduced, approximately 3-4 minutes.
Top steaks with mushrooms immediately and serve. Serve with your favorite veggies or potato dishes!