I, as many, struggled with this, as the ingredient list is misleading.
There are only two things needed, sherry wine and an empty bottle.
Sherry wine is a the top of the ladder, after pushing it right in the general store.
Empty bottle is right next to rosaries on his kitchen counter.
Head to Blouins and simply interact with his makeshift still, and make some caribou. Return to rosaries and trade it for the coat.