With a wooden spoon, muddle tarragon, cucumber, 2 strips orange zest, and the Lillet in the bottom of a pitcher. Let stand for 20 minutes. Strain into a serving pitcher halfway filled with ice; discard solids. Add wine; stir. Divide among six 8-ounce glasses. Garnish each with a tarragon sprig, a cucumber spear, and a strip of orange zest.