Cook the noodles according to package instructions and set aside.
Heat vegetable oil in a large skillet over medium-high heat.
Add minced garlic and stir for 30 seconds until fragrant.
Toss in sliced onion and sauté until translucent.
Add broccoli florets and bell peppers; stir-fry for about 3 minutes.
Push the vegetables to one side of the skillet.
Add cooked noodles to the empty side of the skillet.
Drizzle sesame oil and soy sauce over the noodles.
Mix everything together, ensuring noodles are coated.
Garnish with chopped green onions and serve hot.