Verjus dates back to the middle ages where it was used in lieu of vinegar. Today, the same argument is made for the use of verjus as then...when looking for something less acidic, more gentle, use verjus. Maggie Beer is making a product in Barossa Valley in Australia which rivals the best French verjus. It is made from the unripe juice of green grapes and its mellow crispness will brighten a myriad of dishes. Try the White Verjus as well.
Use verjuice to deglaze a pan after searing chicken or fish - the gentle acidity will blend with the pan juices to create a lovely sauce.