Fennel Vinegar is fennel-flavoured vinegar.
It can be made from white wine vinegar infused either with fresh fennel leaves, or with fennel seed.
Fennel Seed Vinegar
2 cups (16 oz / 500 ml) white wine vinegar
1 1/2 tablespoons of fennel seeds
Sterilize a jar or bottle. Crush the fennel seeds, add them to the jar. Bring the vinegar to a simmer. Pour in into the jar. Let cool, then seal, and let stand at room temperature for 2 weeks, then filter into a clean jar.
Fennel Leaf Vinegar
Well in advance: wash the fennel leaves, shake and pat dry, then let stand for all the water to dry off them completely, an hour or two. (Prepare enough fennel leaf to loosely fill your designated jar or bottle two-thirds full) Sterilize your jar or bottle. Bring to a simmer enough white wine vinegar to fill it. Loosely pack the fennel leaf into it, pour the white wine vinegar over it.Let stand in a dark place at room temperature for 2 weeks, then filter into another bottle. Variation: add a sprig of tarragon as well to the fennel leaf.