Keto Flank Steak with Cauliflower and Broccoli Gratin

Name: Keto Flank Steak with Cauliflower and Broccoli Gratin
Yield: 4
Cuisine: American
Ingredients: 1 cup cauliflower florets, bite-size pieces; 1 cup broccoli florets, bite-size pieces; 1 cup oyster mushrooms; 2 oz cheddar cheese; ½ cup heavy cream; 1 tsp salt; ½ tsp black pepper; 8 oz flank steak; ½ tsp salt; Pinch of pepper; 1 tsp fresh thyme; 2 Tbsp olive oil; Sauce:; ½ cup heavy cream; 1 Tbsp coconut amino; ½ tsp black pepper