Step 1: Prep
Bring a medium pot of salted water to a boil. Wash and dry produce. Trim zucchini and halve lengthwise; thinly slice crosswise into half-moons. Thinly slice scallions, separating whites from greens. Peel and mince or grate half the ginger.
Step 2: Cook the Zucchini
Heat a large drizzle of oil in a large pan over medium-high heat. Add zucchini and cook, stirring occasionally, until lightly browned, 2-4 minutes. Turn off heat, transfer to a plate. Wipe out pan.
Step 3: Make the Sauce
While zucchini cooks, in a medium bowl whisk together cornstarch, ponzu and soy sauce until smooth and no lumps remain. Whisk in stock concentrate, plum jam, gochujang, and ¼ cup water until combined.
Step 4: Cook the Ground Beef (or Ground Pork)
Heat a drizzle of oil in the pan used for zucchini over medium-high heat. Add ground beef; season with a pinch of salt and pepper. Using a spatula, press into an even layer. Cook, undisturbed, until browned on bottom, 3-4 minutes. Break up meat into pieces and continue cooking until beef is cooked through, 2-4 minutes more. Stir in scallion whites, ginger, garlic powder, and ¼ teaspoon sugar. Cook until fragrant, 30-60 seconds. Stir in sauce. Cook until slightly thickened, 30-60 seconds. Turn off heat.
Step 5: Cook the Noodles
Once water is boiling, add ¾ of the noodles to pot (save the rest for another use). Cook, stirring occasionally, until tender, 1-2 minutes. Drain; rinse thoroughly under cold water, 30 seconds. (This stops the cooking and helps prevent sticky noodles.) Add drained noodles, zucchini, and 1 tablespoon butter to pan with pork mixture. Toss until noodles are warmed through and everything is combined. (Tip: If needed, stir in water a splash at a time until noodles are thoroughly coated in sauce.) Taste and season with salt and pepper.
Step 6: Serve
Divide stir-fry between bowls. Top with scallion greens and serve.
