Coffee Caramel Swirl Ice Cream

In a 3-quart heavy saucepan boil sugar, corn syrup, water, and a pinch salt over moderate heat, stirring, until sugar is dissolved. Boil mixture, without stirring, gently swirling pan, until a deep golden caramel. Remove pan from heat and carefully pour cream and vanilla down side of pan (mixture will vigorously steam and caramel will harden). Simmer mixture, stirring, until caramel is dissolved. Remove pan from heat and cool caramel. Caramel swirl may be made 1 week ahead and chilled, covered. Bring caramel swirl to room temperature before using. (If caramel swirl is too stiff to pour, heat slightly.)