Heat oven to 350°F. Spray the pita wedges lightly with olive oil and arrange them in one layer on baking sheets. Bake until they begin to color, about 10 minutes. Sprinkle with salt, turn off oven and put chips back in to keep warm.

In a blender or food processor, combine feta, sour cream or yogurt, 1/4 cup olive oil, garlic, mint and zest and juice of a lemon; sprinkle with salt and pepper. Blend or process until smooth. (You can also mash mixture by hand, with a fork.)

Put remaining tablespoon of oil in a skillet over medium-high heat and cook onions until soft, about 5 minutes. Add lamb and cumin and sprinkle with salt and pepper; continue cooking until meat is cooked through, about 5 to 10 minutes more. Put pita chips on a serving plate and top with lamb, sauce, tomatoes, cucumbers and olives.