Wash chinese cabbage leaves and drain well. Remove stalks maybe.
Peel and chop finely the shallots and mix them well in a bowl with the mustard, vinegar, oil and sugar to a marinade. Season with salt and pepper.
Peel and core tomatoes and dice them.
Fry chicken livers briefly in a nonstick frying pan, simmer a few minutes and and spice with salt.
Arrange chinese cabbage leaves on plates, drizzle with marinade and sprinkle with tomatoe cubes and walnuts. Serve liver warm upon the salad.