Grilled Halibut with Calabrian Chile Gremolata

Name: Grilled Halibut with Calabrian Chile Gremolata
Ingredients: For the fish; 1/4 cup extra virgin olive oil; 2 lemons, zested; 4 (6-ounce) filets of white fish (such as halibut or cod), skin removed if desired; Kosher salt, to taste; Black pepper, to taste; For the gremolata; 1 large bunch parsley (leaves and tender stems); 2 cloves garlic; 2 heaping tablespoons crushed Calabrian chiles; 1/2 cup plus 3 tablespoons extra virgin olive oil; 1 teaspoon red wine vinegar; 1 1/2 teaspoons kosher salt; To finish; Parsley leaves; Flaky salt, to taste