Combine first 4 ingredients in a 2-quart container. Cover and chill 2 hours or up to overnight.
Pour 1 cup of mixture into a 1-quart mason jar. Add ice until ice is just above the level of the liquid. Shake for at least 15 hearty shakes or until mixture is covered with white foam. Strain into glasses. Repeat procedure in batches with remaining mixture. Garnish with star anise, if desired.