Pickled Cucumbers

Thanks to Cornersmith for the lovely recipe:   Ingredients 2 kg (4 lb 8 oz) Lebanese (short) cucumbers (the smaller, the better)  2 tbsp salt 1 litre (35 fl oz/4 cups) white wine vinegar 220 g (7¾ oz/1 cup) caster (superfine) sugar ½ tsp turmeric 2 small brown onions, thinly sliced 3 tsp brown mustard seeds [more]