Prepare the ingredients: gently loosen the Fresh wide rice noodles (sen yai) if they are stuck together by briefly rinsing with warm water or separating by hand; slice the Boneless skinless chicken thighs into bite-sized strips; finely mince the Garlic and the Thai bird's eye chilies (adjust quantity to taste).
Slice the Onion into thin wedges and cut the Red bell pepper into strips; trim and halve the Baby corn lengthwise if large; halve the Cherry tomatoes. Pluck the leaves from the Thai holy basil leaves and set aside.
Mix the sauce: in a small bowl combine the Oyster sauce, Light soy sauce, Dark soy sauce, Fish sauce and a little Water to thin slightly; stir in the Palm sugar until dissolved. Taste and adjust the balance of sweet, salty and savory to your liking.
Heat a wok or large skillet over high heat and add the Neutral oil. When shimmering, add the minced garlic and chilies and stir-fry for about 20–30 seconds until aromatic but not browned.
Add the chicken to the wok and spread it into a single layer; let it sear for 1–2 minutes undisturbed, then stir-fry until mostly cooked through and lightly caramelized, about 3–4 minutes.
Toss in the onion, red bell pepper and baby corn and stir-fry for 1–2 minutes more so the vegetables remain crisp-tender.
Push the contents of the wok to one side, add the noodles, then pour the prepared sauce over the noodles. If the noodles are dry, add a splash of Water to help loosen them and create a silky coating.
Toss everything together vigorously so the noodles absorb the sauce and pick up some char from the wok; continue stirring and flipping for 1–2 minutes until the noodles are heated through and evenly coated.
Add the halved cherry tomatoes and toss briefly just to warm them without breaking them down completely.
Remove the wok from heat and fold in the Thai holy basil leaves so they wilt from the residual heat, releasing their aroma. Taste and adjust seasoning with more fish sauce, soy or palm sugar if needed.
Serve immediately while hot, garnishing with extra basil or sliced chilies if desired. Pad Kee Mao is best enjoyed fresh and smoky from the wok.
