Ms Margarita, who sells Artesanal Dark and White Cholacolate products, also sells Buttermilk on Mondays at Sunrise Restaurant's Monday Market. Her Buttermilk with Probiotics is of higher quality.
Ms Margarita's cellphone number is 332-163-8234. A very nice and accomodating lady.
Gooluck with your wife's recipe ManxMan!
nb: it is called suero de la leche according to google translate