How to Make It
Make the orange-cinnamon syrup: Place orange zest in a heatproof 16-ounce jar and add sugar. Seal jar, and shake to combine. Let stand at room temperature 12 hours.
Bring 1 cup water and cinnamon stick to a boil in a saucepan. Pour into jar and stir to dissolve sugar. Let cool to room temperature, about 1 hour.
Strain syrup and stir in salt. Store in sealed jar in refrigerator up to 1 month.
Make the punch: In a cocktail shaker, combine the rum, port, lemon juice, and syrup. Fill shaker with ice; cover and shake to chill, but not dilute, about 5 shakes.
Place a few large ice cubes in a punch cup, and strain drink over ice. Top with Champagne and garnish with flower.