Heat the vegetable oil in a large skillet over medium-high heat. Add the finely minced garlic and chopped ginger. Cook, stirring constantly, for 2-3 minutes until the mixture is fragrant and just starting to turn golden.

Sprinkle in the crushed red pepper flakes, if you like a bit of heat. Stir well to incorporate the flakes into the aromatic mixture. You just need a few moments here for the chili to become fragrant.

Add the cooked lo mein noodles to the skillet, followed by the light soy sauce, dark soy sauce, and roasted sesame seeds. Toss everything together thoroughly so the noodles are fully coated in the sauce and aromas. Continue cooking for 3-5 minutes until the noodles are heated through. I like to use tongs to toss the noodles for even mixing.

Turn off the heat. Immediately drizzle in the sesame oil and add most of the sliced green onions. Toss the noodles again to coat evenly and gently wilt the green onions with the remaining heat. For a more authentic flavor, I like to use fresh, high-quality sesame oil here.

Transfer the noodles to serving plates. Garnish generously with extra toasted sesame seeds and more sliced green onions before serving. Enjoy your homemade lo mein!