Steak Preparation 1/2: In a bowl, combine 3.9 oz (110 g) 85% lean ground beef, 2 tablespoons (30 ml) breadcrumbs, 1/4 large egg, 1/2 tablespoon ketchup, 1/4 tablespoon Worcestershire sauce, 1/4 teaspoon dry mustard, 1/4 teaspoon soy sauce, 1/8 teaspoon ground black pepper, a pinch of cayenne pepper, and 1/2 tablespoon butter.

Steak Preparation 2/2: Mix with a fork or your hands until well combined. Cover with plastic wrap and refrigerate for at least 2 hours or overnight. Lightly season with salt.

Sauce Preparation 1/2: Melt 1/2 tablespoon butter in a large nonstick skillet over high heat. Add 3 large white mushrooms, 1/2 medium onion, and salt; sauté until well browned, about 5 to 8 minutes. Reduce heat to medium and add 1/2 tablespoon flour; cook and stir for 3 minutes.

Sauce Preparation 2/2: Stir in 3/4 cup (180 ml) beef broth, 1/2 tablespoon ketchup, and 1/4 tablespoon Worcestershire sauce. Increase heat to bring to a boil. Reduce heat to medium and cook, stirring occasionally, until the sauce thickens slightly and reduces, about 10 minutes. Taste and adjust salt if needed. Transfer the sauce to a measuring cup. Scrape the skillet with a spatula.

Shaping the Steaks: Remove the meat from the refrigerator and divide into four equal portions. Moisten your hands and shape each portion into an oval patty about 1/2 inch thick. Lightly season both sides of the steaks with salt.

Cooking the Steaks: Melt butter in the clean skillet over medium-high heat. Add the steaks and cook until browned, about 2 to 3 minutes per side. Pour in the sauce and bring to a boil. Reduce heat to medium and continue cooking until the sauce is hot and the steaks are no longer pink in the center, about 5 more minutes. An instant-read thermometer inserted in the center should read at least 160°F (70°C).

Serving: Serve the steak with the sauce on top, along with mashed potatoes and green beans.