Tarragon vinegar от John Spottiswood

This popular herb vinegar is used to make Béarnaise sauce and vinaigrettes. It's easy to make at home. Just put one or two sprigs of clean, fresh tarragon in a bottle of warm white wine vinegar, tightly seal the bottle, and let it stand for at least a few days. The sprigs will eventually become bitter, so remove or replace them after a few weeks. Make sure that the vinegar you use has an acidity level of at least 5% (this information is given on the label). Don't add too much tarragon to the bottle, or you may reduce the acidity of the vinegar so much that it loses its ability to preserve.