Grilled Fish in a Spicy Citrus Marinade

Name: Grilled Fish in a Spicy Citrus Marinade
Ingredients: 4 firm, mild white fish fillets, such as grouper, sea bass, flounder, cod, halibut or tilapia, each about 6 oz.; Sea salt or kosher salt, to taste; 1 small yellow onion, diced; 1 walnut-sized piece of fresh ginger, peeled and thinly sliced; 1 small bunch fresh cilantro, chopped; 1 Tbs. chopped garlic; 2 tsp. minced jalapeño chili; 2 tsp. grated lime zest; 1 tsp. freshly ground pepper; 1/4 cup lime juice; 1/4 cup olive oil; 1 lime, quartered (optional)