1. Open up the pita bread at the seam, so you have two discs. Toast until golden brown on both sides, then break into bite-sized pieces and place in a bowl. Sprinkle the sumac all over the toasted pita pieces, then add the olive oil and toss well.
2. Remove any damaged outer leaves from the lettuce, then cut across into 1 cm strips.
3. If using a regular cucumber, peel, quarter lengthways and deseed; if using small cucumbers, simply halve lengthways. Cut the cucumber(s) across into slices.
4. Thinly slice the spring onions.
5. Chop the tomatoes into bite-sized pieces.
6. Put all ingredients apart from the bread into a large salad bowl, add the herbs and season with salt to taste. Taste and adjust the seasoning if necessary. Serve immediately.
