Bring a large pot of lightly salted water to a boil. Add the noodles and let the water come back to a boil. Cook the noodles, stirring occasionally, for 4 to 5 minutes, or until they’re tender but still have a slight bite. Drain the noodles and set them aside, keeping them warm.
While the noodles cook, heat 1 tablespoon of oil in a large nonstick skillet over medium-high heat. Add the zucchini, onion, and bell pepper, seasoning with a pinch of salt and pepper. Cook, stirring occasionally, until the vegetables are softened and lightly caramelized, about 8 minutes. Stir in the garlic and cook for another minute until fragrant. Transfer the cooked vegetables to a bowl and set aside.
Heat the remaining oil in the skillet until it’s hot. Add the steak strips and sear them, cooking each side until browned and the steak reaches a medium doneness. Season with a pinch of salt and pepper while the steak cooks for added flavor.
In the meantime, prepare the teriyaki sauce by mixing soy sauce, water, brown sugar, vinegar, cornstarch, and ginger in a bowl. Whisk the ingredients together until the sauce is smooth and fully combined.
Once the steak is cooked, return the vegetables to the skillet and pour the teriyaki sauce over the mixture. Bring it to a simmer and cook for about 2 minutes, allowing the sauce to thicken. Add the cooked noodles and gently toss to coat them evenly with the sauce. Taste and adjust the seasoning if needed for a perfect flavor balance.