In a medium bowl, combine the thinly sliced flank steak with soy sauce, oyster sauce, cornstarch, and a dash of salt and pepper. Mix well until the beef is evenly coated. Cover and let marinate in the refrigerator for at least 15 minutes.
In a large pot, bring salted water to a boil. Add the egg noodles and cook according to the package instructions until al dente, about 4-5 minutes. Drain the noodles and set aside, tossing them with a little oil to prevent sticking.
In a large skillet or wok, heat 1 tablespoon of vegetable oil over high heat. Once the oil is hot and shimmering, add the marinated beef in a single layer. Stir-fry for 2-3 minutes until the beef is browned and just cooked through. Remove the beef from the pan and set aside, keeping it warm.
In the same skillet, add the remaining tablespoon of vegetable oil. Toss in the minced garlic and grated ginger, sautéing for about 30 seconds until fragrant but not burned.
Add the sliced red bell pepper and trimmed snow peas to the skillet. Stir-fry the vegetables for another 2-3 minutes until they are vibrant and tender-crisp.
Return the cooked beef to the skillet along with the drained egg noodles. Drizzle with sesame oil and chili paste, tossing everything together gently over medium heat for 2 minutes until well mixed and piping hot.
Give the dish a quick taste and adjust seasonings as necessary. If you like it spicier, add more chili paste. If you prefer it saltier, add a splash more soy sauce.
Remove from heat and generously garnish with chopped green onions and a sprinkle of sesame seeds.
Notes
Serve in large bowls garnished with green onions and sesame seeds for visual appeal.