This is, justifiably, one of the most popular of the herb butters. Blanch 2ounces (50grams) fresh tarragon leaves for 1 minute in boiling salted water. Refresh the leaves and dry them on a towel. Grind the blanched leaves with a mortar and pestle or in a food processor. Combine the tarragon paste with 8ounces (250grams) butter.