01 - Perform complete mise en place for all components. If using vacuum-packed or dried udon, bring a pot of water to a rolling boil.
02 - Heat a large skillet or wok over medium-high heat. Add 1 tablespoon of unsalted butter and allow it to melt. Introduce the ground turkey and sauté, breaking it apart with a utensil, until it is mostly cooked through and exhibits a light browning, approximately 4–5 minutes.
03 - Add the minced garlic, the white portions of the spring onions, and the trimmed green beans to the skillet. Stir-fry for 2–3 minutes until the green beans are vibrant and develop a slight tenderness.
04 - Concurrently, cook the udon noodles according to the manufacturer's instructions. Fresh noodles typically require 1–2 minutes of cooking, while dried noodles may need 7–8 minutes. Drain the noodles thoroughly and set them aside.
05 - To the skillet containing the turkey and vegetables, add the soy sauce, oyster sauce, hoisin sauce, granulated sugar, freshly ground black pepper, and sesame oil. Stir vigorously to ensure all ingredients are well combined.
06 - Integrate the drained udon noodles into the skillet. Add the remaining 1 tablespoon of butter and toss to coat the noodles evenly. If the sauce appears too thick, incorporate 1 tablespoon of water to achieve a looser consistency.
07 - Continue to stir-fry for an additional 1–2 minutes, ensuring the noodles are completely coated with the sauce and all components are heated through.
08 - Serve the dish immediately. Garnish with toasted sesame seeds, reserved green parts of the spring onions, and chili flakes, if desired.