Properly chill 1 cocktail glass. In mixing glass with ice, pour gin and absinthe, and stir. In your cocktail glass, roll 1/2 oz of dry vermouth and throw away the excess. Strain other ingredients into cocktail glass and float 1/2 oz of grand marnier over top. Garnish with orange peel.
More info on how to make a Absinthe Minded Martini