Cook 200g of wide dried rice noodles according to the package; drain.
Mix 3 tablespoons of oyster sauce, 1½ tablespoons of light soy sauce, 1½ tablespoons of dark soy sauce, 2 teaspoons of sugar, and 1 tablespoon of water.
Heat 2 tablespoons of neutral oil in a wok over high heat. Fry 3 minced garlic cloves and 2 chopped Thai chilies for 10 seconds. Add ½ sliced onion and cook for 1 minute.
Add 200g of boneless chicken thighs, sliced, and 2 teaspoons of fish sauce. Stir-fry for about 2 minutes, until the chicken is cooked through.
Add 2 scallions, cut into short lengths, the noodles, and the sauce. Toss for about 1 minute, until the sauce coats the noodles.
Remove from the heat and toss in 1 cup of Thai basil leaves until wilted.
