Thinly slice the cucumbers lengthways into ribbons and transfer to a bowl. Sprinkle with 1½ tbsp salt, turn to coat then leave to stand for 10 minutes.
Drain the cucumber, rinse with water then drain again. Transfer to a jar and add the vinegar and sugar. Seal with the lid and shake to combine. (The pickle can be used straight away but it will keep in the fridge for up to 2 days.)
Whisk the crumbled feta and labneh in a bowl until smooth. Sprinkle with the sumac.
Arrange the eggs on a plate and sprinkle with more sumac. Serve on a large board with the pickled cucumbers and other accompaniments.