When preparing laban, temperature conditions must be exactly right and the culture must not be disturbed while it is working.
Scald milk and cool to almost lukewarm. Stir the starter, which has
been saved from a previous batch, until smooth. Thin with several
tablespoons of warm milk. Stir starter into rest of milk. Mix
well. Cover bowl with a china plate and wrap in a heavy wool cloth or
blanket. Leave undisturbed in a warm, but not hot, place. In summer
laban usually clabbers in about three hours; in winter it
requires an hour more. When completely clabbered place in
refrigerator. Do not jar the laban and thereby disturb the
curd. Serve cold. Many ways of serving laban are described in
this book. It is equally good with meat, vegetables or fruit. It is
never served with fish, however.