Place all ingredients in a food processor or blender and puree until very smooth.
Transfer the mixture to a small, heavy-bottomed pot and bring to a gentle simmer. Simmer, and to avoid splatters, continually whisk the mixture for 5 minutes, until it is about as thick as tomato ketchup.
Cool to room temperature and place in a tightly sealing jar.
Refrigerate overnight to allow flavours to meld and then serve. Will keep, refrigerated, for up to 2 weeks.
Recipe Options: To make mango sesame ketchup, mix two teaspoons of sesame oil into the ketchup before simmering 5 minutes. Instead of dry sherry, use an equal amount of Chinese rice wine in the ketchup.