How to make it
In a large saucepan over medium heat, combine prosciutto and water. Simmer for 10 minutes. Strain and discard prosciutto. Place stock, uncovered, in refrigerator to cool.
Once cooled, stock will have a solid layer of fat on top. Remove fat and discard it.
In a large bowl, combine stock and Scotch, stirring to mix. Evenly divide mixture among 1-quart glass containers. Cover with cheesecloth, securing it with a rubber band, to keep out debris.
Place containers in a cool, dry, dark place. After 3 to 6 weeks, taste: it should be sharp, tangy, and sour. Or test by using pH strips—shoot for a reading of 4 or below on the pH scale.