In medium heavy-bottomed saucepan, cover and bring rice to boil; reduce heat to low and simmer for 12 to 15 minutes or until water is totally absorbed. Remove from heat. Let stand, covered, for 15 minutes.

Meanwhile, wash and break asparagus stalks where they snap easily; discard ends. Cover in boiling water for 2 to 3 minutes or until fork-tender. Rinse in cold water. Pat dry and slice into 1-inch (2.5 cm) pieces.

With scissors, cut nori sheet along perforated lines. Cut each long strip into 1-1/2-inch (4 cm) squares; set aside.

With fork, gently fluff rice; stir in vinegar. If not using right away, cover with damp cloth. Slice smoked salmon into 1-1/2-inch (4 cm) strips to wrap around asparagus. Combine mustard with mayonnaise.

Lay out nori squares on work surface. Wearing latex gloves, wet hands. Squeeze 1 tsp (5 mL) sushi rice into tight ball; place on work surface and smooth and shape into square or leave round. Place on nori square; immediately place on serving platter. Repeat with remaining rice. Can be covered with plastic wrap and set aside at room temperature until serving time.

Just before serving; place 1/4 tsp (1 mL) mustard mixture on each rice ball. Wrap thin slice of salmon around asparagus piece; place on mustard. Sprinkle with sesame seeds. Serve or refrigerate.