Put the water in the pan, turn the heat on high, add the sugar and stir only long enough to dissolve. Stirring after this point will cause the sugar to form large crystals so shake the pan to keep the heat even. Once you see the syrup begin to darken slightly, turn off the heat, and slowly add the vinegar. The more vinegar you add, the thinner the end result will be. Add the mint, push it around so it is coated with the syrup, and allow to cool. Strain into squirt bottles. Some chefs like to get the caramel a little darker, but I find this to obscure the flavor of the herbs. Strictly a matter of preference. This sauce will keep at room temperature indefinitely, and, if refrigerated, will thicken (temporarily).