Notes: If making up to 2 days ahead, cover and chill; sauce thickens when it's cool.
1. In a 1 1/2- to 2-quart pan, combine port and sugar. With a small, sharp knife, slit vanilla bean open lengthwise. Scrape seeds from pod; add seeds and pod to the port mixture.
2. Boil over high heat, stirring occasionally, until reduced to 1 cup, 10 to 15 minutes. Let sauce cool at least 15 minutes; discard vanilla pod. Serve warm, cool, or chilled.
Nutritional analysis per tablespoon.