Cut chicken against the grain into thin strips. Add 1 teaspoon of soy sauce to the chicken, mix well, and let it rest for 15-20 minutes while you are preparing the rest of the things.
Prepare rice noodles as per package instructions. To avoid overcooking, I prefer adding hot water to the noodles until fully submerged, covering them, and letting them soak for 15-20 minutes. Then drain the noodles and keep them aside.
Clean and cut baby bok choy. Clean and pluck basil leaves.
Mix all the ingredients for the sauce.
Heat a large wok or skillet with 2 tablespoons of oil. When the oil is hot, add the marinated chicken and sear it for 2 minutes on high heat without disturbing it. Flip and sear it again for one more minute. Because the chickens are cut into thin strips, they should be cooked at almost 90% by then. Remove the chicken from the pan and keep it aside, covered. The chicken will cook further in the remaining heat.
Clean the skillet/wok if there are bits of chicken stuck to it. Heat the remaining oil. Saute the sliced onion for about 30 seconds. Add the white part of the green onion after slicing, minced garlic, and red chili (if using). Saute for another 30 seconds-1 minute.
Stir-fry bok-choy for about 30 seconds. Keep the heat on medium-high. Then add drained rice noodles and cooked chicken along with its juices, Thai basil, and green onion. Pour the sauce around the edges of the pan.
Toss everything over high heat until the noodles are coated well with the sauce. Stir fry it for about 2 minutes, scraping the bottom of the pan to prevent the noodles from sticking. ( The secret to street-style smokey noodles is tossing the noodles on high heat for a couple of minutes until it is slightly charred).
Serve hot with more green onion on top.