Ingredients

• 1/3 cup sour cream
• 1 tablespoon chopped fresh chives
• 1 16-ounce package frozen potato-cheese pierogi
• 1 5-ounce package baby spinach
• 1 tablespoon unsalted butter
• 3 tablespoons whole-grain mustard
• 1 tablespoon extra-virgin olive oil
• 2 teaspoons Worcestershire sauce
• 1 1/4 to 1 1/2 pounds flank steak
• Kosher salt and freshly ground pepper

Instructions

1. Preheat a grill to high. Whisk the mustard, olive oil and Worcestershire sauce in a small bowl. Season the steak with salt and pepper, then coat with half of the mustard mixture; let sit at room temperature 10 minutes. Combine the sour cream and chives in another small bowl and season with salt and pepper; refrigerate until ready to use.
2. Transfer the steak to the grill and cook 5 minutes; flip, brush with half of the remaining mustard mixture and cook 5 more minutes. Flip again and brush with the rest of the mustard mixture; cook 5 to 8 more minutes for medium rare. Transfer to a cutting board and let rest.
3. Meanwhile, bring a large pot of water to a boil. Add the pierogi and cook as the label directs. Put the spinach in a colander. Drain the pierogi in the colander with the spinach so the spinach wilts. Return the pierogi and spinach to the pot and stir in the butter; season with salt and pepper.
4. Slice the steak against the grain; divide among plates along with the pierogi and spinach. Top the pierogi with the chive sour cream.
5. Photograph by Justin Walker