Wine Wars: Vermentino - Toussaint (Blood and Wine)
Area: Plegmund's Bridge
Quest Giver: Automatically started during Wine Wars: Belgaard
Other Requirements: Do not complete Wine Wars: Coronata or you will fail this quest. Instead read below
When you arrive at Plegmund's Bridge with the Wine Wars: Belgaard quest you'll find two people by the names of Liam and Matilda arguing. Geralt will automatically speak with both of them as part of the Belgaard quest and they'll both give you their own Wine Wars quest as well. Wine Wars: Vermentino is Liam's quest.
Important: If you wish to do all of the Wine Wars quests then you should not complete this quest. Only do enough of this quest to find the Letter item (pictured below). When you find this item as well as the quest item in the Wine Wars: Coronata you'll unlock Wine Wars: The Deus in the Machina.
Completing Wine Wars: The Deus in the Machina will automatically complete & combine the Vermentino and Coronata quests into one quest, Wine Wars: Consorting. This is the only way you can complete all of the Wine Wars quests.