Chop the onion. Dice the carrot and celeriac, slice the leek and Chinese leaves. Heat the butter, sauté the vegetables and beans for approx. 5 mins. Pour in the stock, bring to the boil, reduce the heat, cover and simmer for approx. 10 mins. Add the pasta, cook uncovered for approx. 10 mins. until al dente, season. Tear off the parsley leaves and sprinkle over the top.