Snap tough ends from asparagus and discard. Place asparagus in 3 cm water in large skillet, bring to boil, reduce heat, cover and simmer until tender, 5 to 8 minutes. Blend egg yolks, lemon juice and salt in saucepan or top of double boiler. Add half of butter and stir constantly over low heat or boiling water until butter melts. Add remaining butter and continue stirring until it melts and sauce thickens. Stir in orange peel and juice. Drain asparagus and serve topped with sauce.