Dressing:

4 teaspoons ground sumac, soaked in 4 teaspoons warm water for 15 minutes
3 tablespoons (or more) fresh lemon juice
2 tablespoons (or more) pomegranate molasses
2 small garlic cloves, minced
2 teaspoons (or more) white wine vinegar
1/2 teaspoon dried mint
3/4 cup extra-virgin olive oil
Kosher salt

Salad:

2 8"-diameter pita breads, halved, toasted until golden brown, broken into bite-size pieces
1/4 cup extra-virgin olive oil
Kosher salt
3 medium ripe tomatoes, chopped, or 4 cups cherry tomatoes, halved
1 pound Persian cucumbers, or one 1-pound English hothouse cucumber, quartered lengthwise, thinly sliced crosswise
6 scallions, thinly sliced
2 Little Gem or baby romaine lettuces, or 1 small head romaine lettuce, trimmed, cut crosswise into 3/4" strips
2 cups (loosely packed) flat-leaf parsley leaves
2 cups purslane leaves or additional 3/4"-strips romaine lettuce
1 cup fresh mint leaves
Ground sumac (optional)