Bring a large pan of seasoned water to a simmer, add the chicken breasts and lower the heat to a gentle simmer. Poach for 8-10 mins or until the chicken is cooked through – test by cutting in half through the thickest part. Transfer to a plate to cool down while you prepare the noodles.
Using a spiralizer fitted with the thicker noodle setting (or a julienne peeler), turn the courgettes and carrots into curly noodles. Tip them into a bowl with the spring onions, beansprouts and soya beans.
In another bowl, mash the peanut butter and soy sauce together to loosen the peanut butter, then whisk in the chilli sauce, sesame oil, lime zest and juice, and 1 tbsp water. When the chicken is cool enough to handle, use two forks to shred it. Add to the vegetables, drizzle over the dressing and gently toss everything together until well coated. Transfer to a platter and scatter over the peanuts and chilli (if using). Leftovers will make a great packed lunch.