1. Light a grill or preheat a grill pan. On four 14-inch-long metal skewers, tightly thread the chicken, pattypans, red onion and tomatillos in an alternating pattern. Brush the skewers with 1 tablespoon of the olive oil and season with salt and pepper.
2. Grill the skewers over a medium-hot fire, turning frequently, until the chicken is just cooked through and the vegetables are lightly charred and barely tender, about 12 minutes.
3. Meanwhile, in a small bowl, combine the mint, parsley, garlic, vinegar and the remaining 2 tablespoons of olive oil; season with salt and pepper.
4. Slide the chicken and vegetables off the skewers and onto plates. Spoon the vinaigrette on top, sprinkle with the feta and serve.
Notes: One serving 323 calories, 14.7 gm total fat, 3.2 gm saturated fat, 12 gm carb.