1.Combine yogurt and salt in medium bowl; spoon into muslin-lined large colander or sieve placed over bowl. Gather corners of muslin together, twist then tie with kitchen string. Place a plate on top of the muslin, then weight with two or three heavy cans; refrigerate 24 hours.
2.Place yogurt in medium bowl; discard muslin and the liquid left in the bowl. Using oiled hands, roll level tablespoons of yogurt into balls; roll in oil then sprinkle with sumac.
3.Serve labne with coppa.
Labne can be left to drain and thicken, still weighted, in the fridge for up to three days.Note