At the 2013 Manhattan Cocktail Classic, Saveur magazine hosted an event called Mandarine Napoleons double buzz; coffee and cocktails (I wasn't there, I found the details online). They made three cocktails combining the brandy liqueur with cold brewed coffee.
I thought this old fashioned was amazing and will be trying the other two soon.
I used the cold brew from Gordon street coffee in Glasgow because they roast their own beans every week but cold brewed coffee is easy to make at home.
I have no idea what cold brewed vinegar is so I used white wine vinegar. It's only two drops but I found that it did improve the balance. If you know better please let me know in the comments.
2&1/4oz rye whisky
3/4oz Mandarine Napoleon
3/4oz Cold brewed coffee
2 drops cold brewed vinegar?
Flamed Orange Twist
Stir all ingredients with ice for a whole minute then strain into a rocks glass over a large cube of ice. Flame a large orange twist over the drink before running it round the rim and adding it to the drink.