If using fresh asparagus, wash and scrape off scales. Break off bases at the point where spears snap easily; discard bases.
Cook asparagus in a small amount of boiling water about 6 minutes or until crisp-tender. (Or, cook frozen asparagus according to package directions, omitting salt.) Drain asparagus and set aside.
Combine white miso, sake or dry sherry, water, and sugar in a small bowl; mix well.
To serve, arrange asparagus on a serving plate. Spoon miso mixture over asparagus; sprinkle with toasted sesame seeds. Makes 8 servings.
To toast sesame seeds, spread a thin layer in a shallow baking pan. Bake in a 350 degree F oven for 7 to 10 minutes or until light brown, stirring once or twice.