How to Make It
If the skin of the cucumber is sweet and tender, leave it on. Otherwise, peel it. Halve the cucumber lengthwise and scoop out the seeds; chop the cucumber into bite-sized pieces. Quarter the onions, slice them crosswise very thin, then combine them with the cucumbers in a bowl.
Wash the purslane in a few changes of waterit's often sandy since it grows along the grounddry it, then break it into small clumps. The whole plant is tender so stems can go in too. Add it to the cucumbers, along with the parsley.
Pound the garlic with a few pinches salt until it's smooth, then add the vinegar and whisk in oil. Check the balance and adjust, if needed. Pour over the vegetables and toss well. Refrigerate for up to one hour before serving.