You can make a concentrate by doing 1 part coarse ground coffee to 4 parts water - leave in fridge for 72 hours. Filter through a paper filter before using
Normal cold brew strength would be 1:16 so this is a 4 x concentrate.
More complexity and depth - if you can pick up Punt e Mes, try using it in place of 25% of the sweet vermouth in the Negroni - you'll taste the difference
Normal cold brew strength would be 1:16 so this is a 4 x concentrate.