Coarsely chop the choy sum, keeping the leaves and stems separate. Trim the beans. Peel the ginger and cut into very thin matchsticks.
Step 2 — Prep ingredients
DOUBLE THE CHICKEN OPTION Thinly slice the chicken into strips. Combine half the ayam goreng paste* and 2 tbs water in a bowl. Bring a medium saucepan of water to the boil for the noodles.
Step 3 — Make topping
Heat 2 tsp oil in a large deep frypan over medium-high heat. Add the ginger and cook, stirring, for 1 min or until fragrant. Add the peanuts and cook, stirring, for 1 min or until golden and crisp. Remove the ginger and peanuts using a slotted spoon and drain on paper towel.
Step 4 — Start stir-fry
Heat 2 tsp oil in the same pan over medium-high heat. Stir-fry the chicken, in two batches, for 2 mins or until golden. Return the chicken to the pan, add the choy sum stems and beans and stir-fry for 3 mins or until tender.
Step 5 — Cook noodles
Meanwhile, cook the noodles in the pan of boiling water for 2 mins or until tender. Drain, then rinse under hot water to prevent the noodles from sticking.
Step 6 — Finish stir-fry and serve
Add the noodles, choy sum leaves and ayam goreng mixture to the chicken mixture and stir-fry for 1-2 mins until combined and the chicken is cooked through. Taste, then season with salt and pepper. Divide the chicken stir-fry among bowls. Scatter over the crispy peanut-ginger topping to serve.