This is a classic caramel sauce. It will set up in the fridge, but can be easily warmed and re-warmed as needed.
Place the water, sugar and corn syrup (or lemon juice) in a medium saucepot and have the cream and butter measured and on hand. Bring the sugar up to a full boil on high heat without stirring and continue to boil, occasionally brushing down the sides of the pot with water, until the sugar turns a light amber colour, about 5 minutes. Remove the pot from the heat and whisk in the cream and butter, watching out for the steam and bubbling. Once the bubbling subsides, add the vanilla and salt. Set aside to cool while preparing the other components (but the caramel can still be warm when using).