Cook asparagus in 1/2-inch lightly salted boiling water in large skillet for 5 to 7 minutes or until tender. Drain and cool the asparagus in an ice-water bath. When cooled, drain and place on serving dish. Cover and refrigerate.
Bring chicken broth to boiling in a small saucepan. Turn off the heat; add the saffron and tarragon. Cover and let stand for 4 minutes. Pour into a medium-size bowl to cool. Add orange zest, orange juice, salt and mayonnaise. Whisk together and refrigerate the sauce, covered, for 2 hours. The sauce can be made a day ahead.
To serve, pour the sauce over the asparagus.