In a saucepan combine liqueur, honey, berries, sugar, and salt and simmer on medium-high heat until reduced by half. Remove from heat and allow to cool completely. In a mixing bowl, combine reduction, butter and tarragon until well combined. Remove butter from bowl and spoon onto parchment paper. Roll into a log, using edge of baking sheet to form a tight log. Chill for 2 hours before serving.