- 1/2 vanilla bean, halved lengthwise
- 1 cup dry red wine
- 1 1/3 cups sugar
- 1/4 cup water
- 1 tablespoon unsalted butter
- Scrape seeds from vanilla bean into a small heavy saucepan, then add pod and wine. Boil over moderate heat until wine is reduced to about 1/2 cup, about 10 minutes. Discard pod.
- While wine is reducing, bring sugar and water to a boil in a 2-quart heavy saucepan over moderate heat, stirring until sugar is dissolved. Boil, without stirring, washing down any sugar crystals on side of pan with a pastry brush dipped in cold water, until syrup turns pale golden. Continue to cook caramel, swirling pan, until deep golden.
- Remove from heat, then carefully pour wine down side of pan (caramel will vigorously steam and harden). Simmer, stirring, until caramel is dissolved and sauce is thickened, about 5 minutes. Stir in butter and serve warm.