Created by SassyCook on July 23, 2013
Step 1: In a food processor fitted with the metal blade, process the horseradish until finely grated. Scatter the lemon zest and salt over the top and pulse once or twice until evenly distributed. Add the butter and process until smooth, creamy, and well combined, about 6 pulses. Add the parsley and pulse just until evenly distributed.
Step 2: Place a 2-foot-long sheet of parchment paper or plastic wrap on a work surface. Using a rubber spatula, spread the butter into a rough log about 8 inches long and 1 1/2 inches in diameter.
Step 3: Wrap the parchment or plastic wrap snugly around the log and, using your palms, roll the log back and forth to shape it into a smooth, uniform cylinder.
Step 4: Twist both ends like a candy wrapper to seal.
Step 5: Refrigerate for up to 5 days or freeze for up to 3 months.