1
Preheat the oven to 450°F.
2
Toss the potatoes on a baking sheet with the oil, salt, and pepper. Roast until the potatoes are fork-tender, but not mushy, about 15-20 minutes.
3
Toss the mushrooms with 1 tablespoon olive oil on a baking sheet and roast for 8-10 minutes, until tender.
4
In a large skillet, melt the butter over medium-low heat. Add the onions and cook, stirring, until translucent but not colored, reducing the heat as necessary. Add the thyme, garlic and ½ teaspoon salt. Stir in the roasted mushrooms, balsamic, beef stock, and soy sauce and simmer until thickened and syrupy. Season with salt and pepper to taste and stir in parsley.
5
To make the blue cheese cream, melt the butter in a small saucepan. Stir in the flour and cook for 5-10 minutes over low heat, until the raw flour smell is gone. Add the shallot and cook for 2 minutes. Whisk in the milk and bring to a simmer over medium heat. Reduce to low and stir in the blue cheese until melted, about 5 minutes. Season with salt and pepper to taste and finish with fresh parsley.
6
Reduce the oven to 350°F.
7
Heat the oil in a large skillet or grill over high heat. Add the steaks and sear each side for 1-2 minutes, until crisp and dark brown. Transfer to a baking sheet and finish cooking in the oven to your desired doneness, 8 to 12 minutes. Rest for 5 minutes before slicing on the diagonal.
8
To serve, divide the steak and potatoes between plates. Top with balsamic onions and mushrooms and drizzle with blue cheese cream.