Begin by slicing your boneless chicken thighs or breasts into thin pieces. In a medium bowl, marinate the chicken with light soy sauce and a sprinkle of baking soda. Allow it to rest for about 10 minutes at room temperature.

While the chicken marinates, combine the sauce ingredients in a separate bowl. Mix together sesame oil, oyster sauce, dark soy sauce, sugar, rice vinegar, and a small splash of water.

Heat a large pan or wok over medium heat and add a drizzle of vegetable oil. Once the oil is shimmering, toss in the finely chopped garlic and ginger. Stir-fry for about 30 seconds, until fragrant and golden brown.

Add the marinated chicken to the hot pan, spreading it out evenly. Cook for approximately 1-2 minutes, stirring constantly until the chicken is golden brown and cooked through.

Fold in the flat rice noodles into the pan with the chicken. Pour the prepared sauce over the noodles, using tongs or a spatula to thoroughly mix and coat everything. Allow to cook for about 1 minute until heated through.

Add the sliced bell peppers to the pan and stir-fry the mixture for around 1 minute. Then toss in the bean sprouts and spring onions, cooking for another minute until crisp yet tender.

Remove the pan from heat and give everything a final stir. If desired, garnish with sesame seeds or additional spring onions. Serve hot.