Using a Y-peeler, remove orange peel in long strips. Using a small paring knife, carefully remove any white pith from peel. Reserve remaining orange for another use.

In a 10-inch stainless steel skillet, stir together orange peel, port, and all remaining ingredients. Bring to a boil over medium-high heat. Reduce heat to medium, and cook, stirring occasionally, until thickened and reduced to ⅓ cup, 12 to 15 minutes.

Strain mixture through a fine-mesh sieve into a medium bowl. Finely chop 1½ teaspoons (5 grams) cooked orange peel; reserve for Mulled Spice Brownies. Discard remaining solids. Let syrup cool completely before using.