Adapted from
Falastin: A Cookbook by Sami Tamimi and Tara Wigley
If decent tomatoes aren't available, substitute 2 cups (380g) of halved or quartered cherry tomatoes. I don't advise overdraining the cucumbers with salt in step #2 as they can get soggy. It's a step they don't do in the book, but I like to do it to get rid of some of the excess water. I supposed if you're serving the salad right away, it's not necessary, although it's a habit of mine to do it.
Fattoush often uses stale or day-old bread, which often isn't as crisp as bread that's lightly oven-toasted. To make the toasted bread, put the flatbreads directly on the rack of a moderate oven (about 350ºF/180ºC) for a few minutes to dry them out.
For making the salad ahead of time, you can prepare most of the ingredients in advance; dress the sumac onions, put all the chopped ingredients (except the bread) in a large bowl, and mix up the dressing separately. Then toss everything together just before serving.
Note: This recipe makes about four servings as a main course, six servings as a side salad.