Gremolata: Stir together parsley, lemon zest and juice, garlic, anchovy and oil in a bowl; set aside.
Boil potatoes and garlic in pot of water for about 8 minutes or until tender. Drain and let cool slightly. Quarter potatoes and place in bowl with garlic.
Heat oil in skillet over medium high heat; cook potatoes, stirring occasionally for about 10 minutes or until golden and crispy. With a slotted spoon remove to bowl; toss with thyme and 1/4 tsp each of the salt and pepper. Set aside.
Return skillet and oil to medium high heat; sauté mushrooms with 1/4 tsp each of the salt and pepper for about 5 minutes or until golden; set aside.
Heat a cast iron skillet over high heat; add 1 tbsp of oil. Sprinkle steaks with remaining salt and pepper. Sear both sides of steaks well. Reduce heat and cook until digital thermometer reaches an internal temperature of 140˚F (60˚C).
Remove steaks from heat and let rest for 10 minutes.
Pour steak juices in small saucepan with beef broth and boil until reduced to 1/2 cup. Whisk in butter to thicken sauce.
Smear Gremolata onto plate and place steak on top. Spoon mushrooms and potatoes around steak. Spoon sauce over steak to serve.