Preheat the oven to 400 degrees F.
Mix 1/4 cup of the olive oil with the cumin and paprika in a small bowl. Split each pita horizontally into 2 rounds and brush the rough sides with equal amounts of the oil mixture. Cut the rounds into small triangles or 1-inch pieces and arrange in 1 flat layer on a large baking sheet. Bake until golden and crisp, about 5 minutes. Sprinkle with salt when just out of the oven.
Whisk the vinegar, mustard, salt, and pepper in a large serving bowl until blended. Slowly pour in the remaining 6 tablespoons of olive oil, whisking to form a smooth dressing.
Just before serving, pile the arugula and mesclun in the center of the bowl on top of the dressing. Surround with the peppers, tomatoes, chickpeas, feta, pickles, and chicken. Add the pita croutons, toss and serve.
Recipe courtesy of Sara Moulton Cooks at Home, Broadway Books, 2002