Same remark as Amar about Basel 
(Actually there IS a very good reason for an irish flute player to go to Basel: that’s the city of the maker Tom Aebi.)
Anyway in Strasbourg, It was on the first wednesday of the month in a pub called “La Hache” (the axe). Hope it still exists… One of the most terrible pub I have ever seen, but I remember some VERY good sessions here.