2 spanish onions thinly sliced
½ cup fresh lemon or lime juice
1 teaspoon of caster sugar
¼ cup coriander leaves coarsely chopped
2 teaspoons sumac
Combine onion, sugar and juice in a small bowl. Season with salt and toss. Let sit, tossing occasionally, at least 20 minutes.
Just before serving, drain onion and toss with cilantro and sumac.