Prepare the noodles: Cook the noodles according to the package instructions, reducing the cook time by one minute so they stay firm. Rinse under cold water and set aside.

Start the stir-fry: Warm a large skillet over medium-high heat. Add olive oil, garlic, and ginger, cooking for about 30 seconds.

Brown the beef: Add the ground beef and cook for 2–3 minutes, breaking it apart until browned.

Create the sauce: Stir in the sweet chili sauce, brown sugar, soy sauce, dark soy sauce, and rice vinegar. Let the mixture simmer for 2–3 minutes until it thickens and becomes glossy.

Add vegetables: Add the frozen vegetables, cover the skillet, and cook for 2–3 minutes, or until tender.

Thicken the mixture: Whisk the water and cornstarch together, then pour into the skillet. Cook for 1–2 minutes, stirring, until the sauce thickens.

Finish with noodles: Add the noodles and most of the scallions, tossing until the noodles are heated through.

Serve: Spoon into bowls and garnish with the remaining scallions and a drizzle of chili oil, if desired.