Boil the rice noodles as per the package instructions until tender, then drain and set aside. In a small bowl, thoroughly whisk together the oyster sauce, soy sauce, fish sauce, brown sugar, water, and chili paste to form a cohesive sauce.
Heat one tablespoon of oil in a large skillet or wok over high flame. Sauté the chopped shallots and sliced carrots for about two minutes until slightly softened. Introduce the second tablespoon of oil along with the chicken pieces, seasoning lightly with pepper, and cook thoroughly. Stir in the minced garlic and ginger, letting them release their aroma for about 10 seconds.
Incorporate the zucchini, green bell pepper, tomato slices, and the white parts of the green onions. Cook for another two minutes, stirring frequently.
Add the drained noodles into the pan, then pour the prepared sauce over the mixture. Toss everything together to ensure even coating, and let it heat through for several minutes.
Take off the heat and gently fold in the chopped Thai basil. Serve promptly, garnished with the remaining green onion tops and, if desired, a dash of extra chili paste, sriracha, or crushed red pepper for heightened spice.