Baked Cod with Tomatoes and Onions

Name: Baked Cod with Tomatoes and Onions
Ingredients: 1 (2 to 5-pound) line caught cod fillet with the skin-on; 3 tablespoons extra-virgin olive oil; 1 tablespoon plus 1 teaspoon kosher salt; 11/2 teaspoons ground black pepper; 5 large Roma plum tomatoes, stem ends removed, sliced lengthwise; 1 1/2 cups sliced yellow onions; 2 tablespoons minced garlic; Olive Spread, recipe follows; Cilantro sprigs, for garnish; 1 tablespoon minced shallots; 2 cups pitted brine-cured black olives; 1 tablespoon minced garlic; 1 tablespoon capers, drained; 4 anchovy fillets; 1 tablespoon chopped parsley; 2 tablespoons lemon juice; 1/4 cup extra virgin olive oil; 1/4 teaspoon freshly ground black pepper