Peel the asparagus from the head. Cut the ends freshly. Bring plenty of salted water to the boil. Cook the asparagus in it for about 15 minutes, depending on their thickness. Drain and set aside.
Chop the onion for the dressing. Mix with balsamic vinegar, oil and mustard. Season to taste with salt and pepper. Peel the oranges including the white skin, remove the fillets between the membranes with a knife and cut into bite-sized pieces. Coarsely chop the pistachios.
Mix the asparagus with the dressing, orange fillets and pistachios. Arrange the asparagus salad. Pluck the chervil on top and serve. Serve with fresh walnut bread.