This can be made in advance; store in an airtight container in the refrigerator. Reheat before serving.
1. Heat olive oil in a sauté pan over medium heat. Add shallot, and cook, stirring constantly, about 1 minute or until tender. Add vinegar, and reduce slightly, about 30 seconds. Remove pan from heat, and slowly whisk in mustard and cream until well blended. Stir in tarragon, and season with sea salt and pepper. Drizzle warm over poached eggs.