1. Place the tomatillo, cilantro, lime zest, garlic, jalapeño pepper, and salt in a food processor and thoroughly combine. Add the butter and combine until just blended.
2. Scoop the flavored butter onto a piece of waxed paper and roll into a cylindrical shape. Refrigerate for at least 1 hour.
3. Slice off “coins” of the butter to serve with boiled or grilled corn.
Makes about 1/2 cup; serves 8 to 10