Bring a medium saucepan of salted water to a boil over high heat. Fill a large bowl with ice water.
Meanwhile, peel the baby carrots and remove all but about 1/2 inch of the green stems. Boil the carrots until barely tender, about 5 minutes. Immediately drain the carrots and then immerse them in the bowl of ice water.
In a small saucepan, toast the coriander seeds over medium heat just until they become fragrant and lightly browned, 3 to 5 minutes. Add the white wine and boil until reduced to about 1/4 cup, 6 to 10 minutes.
In a medium saucepan, heat the honey over medium-high heat until it bubbles, about 3 minutes. Add the Champagne and sherry vinegars, and then the coriander and wine mixture; simmer for 5 minutes—watch carefully and reduce the heat as necessary to prevent a boil-over.
Arrange the carrots upright in a clean 1-qt. canning jar or other nonreactive container, and pour the honey mixture over the carrots. Let cool to room temperature. Cover and refrigerate for at least 4 hours but preferably 24 hours before serving the pickles. They will keep, refrigerated, for 2 to 3 weeks.