Begin by cooking the rice noodles according to package instructions until al dente. Drain and rinse them under cold water to prevent sticking. Set them aside.
In a bowl, combine the sliced chicken with baking soda. Let it sit for about 15 minutes. This will help tenderize the chicken, making it juicy and flavorful.
In a small bowl, whisk together the oyster sauce, soy sauce, rice vinegar, white vinegar, dark brown sugar, molasses, and fish sauce. Set this aside as your stir-fry sauce.
In a wok or large skillet, heat 2 tablespoons of vegetable oil over medium-high heat. Once hot, add the marinated chicken in a single layer and cook for about 3-4 minutes, or until browned and cooked through. Remove the chicken from the pan and set it aside.
In the same pan, add another tablespoon of vegetable oil. Add the garlic and serrano chile, stirring for about 30 seconds until fragrant. Then, add the broccolini and stir-fry for 2-3 minutes until tender yet still vibrant.
Return the cooked chicken to the pan along with the drained rice noodles. Pour the stir-fry sauce over everything and toss well to combine, ensuring the noodles are coated evenly. Cook for an additional 2-3 minutes to heat everything through.
Push the noodle mixture to one side of the pan and add the remaining tablespoon of oil to the empty side. Crack the eggs into the pan, scrambling them until just set before mixing them into the noodle dish.
Once everything is well combined and heated through, remove from heat. Serve the Thai-Style Stir-Fried Noodles with Chicken and Broccolini hot, garnished with additional sliced serrano chile if desired.