Mix together the yogurt, salt and lemon juice. Tip the mixture into a doubled-over cheesecloth sat in a sieve or small colander. Place over a bowl, fold the cheesecloth over the yogurt mixture and refrigerate for 12-24 hours. The longer you leave it, the firmer it will become.
When ready, gently squeeze any excess liquid and transfer to a small dish/plate. I'd suggest serving as I have here topped with zaatar and olive oil, but you can also sweeten it up topped with a little honey and nuts.