Soak the mustard seeds in white wine overnight. This softens the seeds and releases their flavors.
Blend the soaked mustard seeds, wine, and white wine vinegar in a food processor until it reaches your desired consistency.
Add honey, garlic, salt, and tarragon. Blend again.
Pour the mixture into a saucepan and simmer over low heat for 10-15 minutes. Stir occasionally.
Let the mustard cool and then transfer it to a jar. Refrigerate for at least two days before using to allow the flavors to meld.
