Clean, wash and cut the soup greens into large pieces. Peel and halve the onion. Wash the chicken breasts. Put everything with approx. 2 1⁄4 l water, 2 teaspoons salt, 2 teaspoons Szechuan pepper and bay leaf in a big pot and bring to boil.
Skim foam from time to time and simmer at medium heat for about 40 minutes.
In the meantime, put the pasta in plenty of boiling salted water and cook according to the instructions on the packet. Clean the leek, wash thoroughly and cut into rings. Wash parsley, shake dry and chop.
Crush 1 teaspoon Szechuan pepper in a mortar. Drain the noodles and let them drain.
Pour broth through a sieve and return to the pot. Bring to the boil. Cover the leek and simmer for about 15 minutes. Remove flesh from skin and bones, cut into small pieces. Add the noodles and half of the parsley to the soup.
Season to taste. Sprinkle soup with the rest of the parsley and crushed Szechuan pepper. Serve with brown bread and lemon-pepper butter.