In a large saucepan, bring water to a boil; add asparagus. Cook for 3 minutes or until crisp-tender. Drain and rinse under cold water; pat dry and set aside.
In a small bowl, combine the cream cheese, egg substitute, onion, tarragon, salt and pepper; set aside. Place one sheet of phyllo dough on a work surface with a short side toward the bottom; spray with cooking spray. Repeat with one more sheet of phyllo. Keep remaining phyllo covered with plastic wrap and a damp towel to prevent drying.
Spread 2 rounded tablespoons of the cream cheese mixture over the bottom third of the rectangle to about the size of a salmon fillet. Top with six asparagus halves and one salmon fillet. Fold sides and bottom edge over fillet and roll up enclose salmon; trim end of phyllo if necessary. Spray with cooking spray.
Place seam side down on an ungreased baking sheet. Repeat with remaining ingredients. Bake at 400° for 15-20 minutes or until golden brown.