Potato and Asparagus Salad with Arugula and Prosciutto
Rinse asparagus and snap off woody ends. Peel the lower third of each stalk and cut diagonally into pieces. Peel, rinse and slice potatoes. Bring a pot of salted water to a boil with butter and sugar. Add asparagus and potatoes and simmer about 12 minutes. Drain, reserving 200 ml (approximately 1 scant cup) of the cooking water.
Mix reserved cooking water with vinegar and season with salt and pepper. Whisk in oil and pour dressing over asparagus and potatoes. Let marinate about 20 minutes. Rinse arugula and shake dry. Cut prosciutto into strips. Toast pine nuts in a dry frying pan.
Combine vegetables with prosciutto and arugula and serve sprinkled with pine nuts.