Instructions

1. Thinly slice 1 large yellow onion (about 2 cups). Thinly slice 8 ounces cremini or button mushrooms (about 3 cups). Thinly slice 2 garlic cloves. Cut 1 pound chuck or ribeye steaks crosswise into 1/2-inch-thick slices, then season with 1 teaspoon of the kosher salt and 1/4 teaspoon of the black pepper. Measure out 1/4 cup sour cream and let sit on the counter to come to room temperature.
2. Heat a large skillet over medium-high heat. Add 2 tablespoons of the unsalted butter. When melted, add the steak and spread out in an even layer. Cook until seared and browned on the bottom, about 3 minutes. Toss and cook until just cooked through, about 2 minutes more. Transfer to a plate.
3. Add the remaining 2 tablespoons unsalted butter to the skillet. Add the onions, garlic and mushrooms and cook until the mushrooms begin to release their liquid, about 5 minutes. Add the remaining 1/2 teaspoon kosher salt and cook, stirring occasionally, until the mushrooms and onions are tender and the onions are beginning to caramelize, about 7 minutes.
4. Add 1/4 cup dry white wine and cook until evaporated, about 3 minutes. Add 1 tablespoon tomato paste and stir until it coats the mushrooms and onions and darkens in color, about 2 minutes.
5. Sprinkle 2 tablespoons all-purpose flour into the pan and toss to coat. Add 2 cups low-sodium beef broth, 1 tablespoon Worcestershire sauce, 1 tablespoon Dijon mustard, 1 teaspoon hot paprika, and the remaining 1/4 teaspoon black pepper. Stir and bring to a boil.
6. Return the beef and any accumulated juices to the pan. Partially cover with a lid and reduce the heat to maintain a low simmer. Simmer, stirring occasionally, until the beef is tender, 60 to 70 minutes. Meanwhile, prepare the dumplings and garnishes about halfway through the cooking time.
7. Fill a large pot with water and bring to a boil over medium-high heat.
8. Place 1 cup all-purpose flour, 1 teaspoon baking powder, and 3/4 teaspoon kosher salt in a large bowl and whisk to combine.
9. Place 1/2 cup whole milk and 1 tablespoon unsalted butter in a microwave-safe measuring cup or small bowl. Microwave until the butter is melted, stirring halfway through, about 1 minute total. Pour into the flour mixture and stir with a wooden spoon or rubber spatula until all the liquid is incorporated and there are no visible dry spots. Let rest for about 5 minutes.
10. Coat a baking sheet with vegetable oil. Once the water is boiling, scoop and drop the flour mixture into the water 1/2 tablespoon at a time. Let the dumplings rise to the top and continue to simmer until they have no dry spots in the center, are cooked through, and are smooth with some bumps and dimples, about 5 minutes. Transfer with a spider or slotted spoon onto the greased baking sheet. You should have about 25 dumplings.
11. Finely chop fresh chives and parsley leaves until you have 2 tablespoons each.
12. When the stroganoff is ready, add 1 tablespoon freshly squeezed lemon juice and stir to combine. Taste and season with more kosher salt, black pepper, or Worcestershire sauce. Add half of the sour cream and stir to combine. Transfer cooked dumplings to a serving dish. Serve the stroganoff over the dumplings. Garnish with a small dollop of the remaining sour cream, parsley, and chives.