Place the shallots in a small bowl. Cover with the vinegar and the lemon juice. Set the shallots aside to pickle at room temperature for 3 hours.
Place the pita in a large bowl and add olive oil, salt, and crushed red pepper flakes. Bake for 7-10 minutes or until the pita is golden. Set it aside to cool.
Drain the dates and place them in a large food processor. Add the garlic and the remaining olive oil. Blitz until a paste forms. Drain the pickled shallots, reserving the pickling liquid.
With the food processor set to low, stream in the pickling liquid and blitz until you have a creamy vinaigrette. Whisk in the remaining salt and the sumac.
Place the chickpeas, cucumber, radish, sugar snap peas, feta, dill, mint, and half of the pita chips in a large bowl.
Add the dressing and toss to coat. Transfer the salad to a platter and garnish with the pickled shallots, the remaining pita chips, dill and mint leaves, and a sprinkling of sumac.