You can make this recipe with a mix of fennel and carrots, or with green beans; we made one batch of each.
Stir together vinegar, sugar, salt, coriander, fennel, and bay leaves in a medium saucepan. Bring to a boil, stirring until sugar has dissolved. Stir in green beans or fennel and carrots. Remove from heat; let cool completely. Cover, and refrigerate at least overnight or up to 1 week.