Mix yogurt, 3 tablespoons of the oil, lemon juice, 1 of the garlic cloves, oregano, and a generous sprinkling of salt and pepper in a medium bowl. Pour half the yogurt mixture in quart zipper-lock bag; add chicken and let stand at least 30 minutes and up to 2 hours. (Can be refrigerated for 2 days.) Reserve remaining yogurt mixture as the salad dressing.
When ready to serve, heat a gas grill igniting all burners on high for at least 10 minutes or build a hot charcoal fire. Clean grate with a wire brush and then lubricate well with an oil-soaked rag. Meanwhile, put arugula, tomatoes, cucumbers, onion, feta, and olives in a large bowl. Mix remaining 4 teaspoons of oil with remaining 2 garlic cloves and brush over one side of each pita.
Place chicken on hot oiled rack and grill until impressive grill marks form, about 3 minutes. Turn chicken over with a spatula and continue to cook until chicken is just cooked through, about 2 minutes longer. Add pitas, oiled side up, the last 2 minutes of grilling. As chicken comes off the grill, turn pitas and continue to grill until golden brown on remaining side, another 1 to 2 minutes.
Place a pita on each of 4 pasta plates. Toss salad with dressing, mounding a portion of salad on each of the pitas. Serve.
Notes
Don’t feel like grilling outside? Use a countertop or stovetop grill instead. Or, saute the chicken in a large, hot oiled skillet for about the same amount of time as the grilling instructions and bake the pitas in a 425-degree oven (or toaster oven) until crisp and golden, about 8 minutes.
Recipe by Three Many Cooks at https://threemanycooks.com/recipes/salads-and-sides/grilled-chicken-souvlaki-salad/