I am a fan of sour beers, especially the gueuze beers. A gueuze beer is a blend of two or more lambic beers which have aged a different amount of years.
I wondered whether a could brew a lambic style of beer and do some blending myself. The problem here is that a lambic beer takes wild yeasts, and these yeasts are very difficult to cultivate. However, the Wyeast company has packages of liquid yeasts that are a blend of (some of) these wild yeasts.
In 2015 I started with the first batch of 'lambic' beer, and continued to do so every year. In 2017 I made my first blend consisting of beer from the 2015 and the 2016 batches. I have baptized it as Bueuze.
The next years, I continued the blending with beers of one and of three years old, which seems to be a standard for a gueuze.
I am very pleased with the result, and I have continued with the Bueuze in the yearly program.
Another type of sour beers I like is the Vlaams (oud) bruin (Flemish (old) brown). It may be that originally these beers where brewed with wild yeast also, but the current one take cultivated yeast.
I started brewing this type of beer in 2018 and used Wyeast Roeselaere. Part of these brews I bottle immediately and the rest I use for blending. In 2019 I blended a 1 year old Vlaams bruin with a 1 year old lambic.
At the moment, I am waiting until I can blend 1 and 3 year old Vlaams bruin.