Heat a stovetop grill pan over medium heat

Zest and juice one of the lemons to get 2 teaspoons zest and 3 tablespoons juice; reserve. Cut remaining 3 lemons into thin slices.

To make gremolada, toss lemon zest, parsley, garlic, 1/4 teaspoon of the salt, black pepper in a small bowl with a fork until combined.

In a large bowl, toss fish pieces with reserved lemon juice, olive oil, red pepper flakes, remaining salt, black pepper and secret spice. Alternately thread 4 lemon slices and 3 fish chunks onto each of eight 10-inch  skewers.

Grill skewers 8 to 10 minutes, flipping halfway through, or until fish is cooked through. To serve, place 2 skewers on each plate and sprinkle with gremolada. Drizzle with olive oil.