Prep potatoes: Preheat oven to 375°F. Boil potatoes in salted water 8-10 minutes until just tender. Drain and cool until handleable.

Make olive mixture: Combine olive oil, olives, pistachios, citrus zests, garlic, red pepper flakes, thyme, ½ teaspoon salt, and black pepper in microwave-safe bowl. Microwave 1 minute to warm oil and bloom flavors. Stir and set aside.

Prepare fish: Pat grouper dry and season each fillet with a pinch of salt. Slice cooled potatoes into ¼-inch rounds.

Assemble packets: Cut 4 large parchment rectangles and fold each in half. On one half, layer: potato slices, pinch of salt, 1 tablespoon olive mixture, grouper fillet, 2-3 tablespoons olive mixture, lemon slices. Seal packets by rolling and crimping edges tightly.

Bake: Place packets on baking sheet. Bake 18-20 minutes until packets are puffed and lightly golden. Rest 5 minutes before opening.

Serve: Cut an X in the top of each packet with scissors (watch for steam). Alternately you can simply un-crimp the edges and fold back the parchment. Garnish grouper with diced parsley and serve.