How to Make It
Preheat oven to 400°F. Toss potatoes with 1 tablespoon of the oil and 1/4 teaspoon each of the pepper and salt on a rimmed baking sheet. Roast potatoes until golden and tender, about 20 minutes, stirring halfway through baking.
Meanwhile, heat remaining 1 tablespoon oil in a heavy skillet over medium-high. Sprinkle beef with 1/4 teaspoon of the pepper and remaining 1/4 teaspoon salt. Sear beef until browned on all sides and a thermometer registers 130°F to 135°F (for medium-rare), about 3 minutes per side, or to desired degree of doneness. Transfer beef to a plate; let rest 5 minutes before slicing.
Return skillet to medium-high. Add mushrooms and garlic, and cook, stirring often, until browned, 2 to 3 minutes. Stir in 2 tablespoons water and Worcestershire, and cook 1 minute. Remove mushroom mixture. Add tomatoes to skillet; cook, stirring occasionally, until blistered, about 4 minutes. Remove from heat.
Stir together buttermilk, vinegar, 1/2 cup of the blue cheese, and remaining 1/2 teaspoon pepper in a large bowl. Toss spinach in butter milk mixture.
Serve spinach topped with potatoes, beef, mushroom mixture, and tomatoes; sprinkle with remaining 1/4 cup blue cheese.
Also appeared in: Health, March, 2020