Cook noodles: Boil noodles according to package instructions. Drain and set aside.
Heat sauce: In a pan, heat sesame oil over medium heat. Add minced garlic and sauté for 30 seconds until fragrant.
Add noodles: Add cooked noodles to the pan.
Add seasoning: Pour in Sriracha, soy sauce, and chili flakes (if using). Toss well to coat the noodles evenly.
Cook briefly: Stir-fry for 1–2 minutes until heated through.
Garnish: Remove from heat and garnish with chopped spring onions.
Serve: Serve hot as a spicy and quick meal.