In a wok or large frying pan heat the oil until hot. Stir fry the Broccolini, red and yellow peppers and spring onions over a high heat for about 3 minutes, or until they are starting to soften a little.
Add the cooked chicken, garlic, chili and ginger and fry for a further 2 minutes.
In a small bowl mix the peanut butter and soy sauce together, then pour into the wok, stirring well to coat everything.
Stir through the cooked noodles and serve immediately.