Catfish with Black Bean and Avocado Relish

Name: Catfish with Black Bean and Avocado Relish
Ingredients: 6 (4 ounce) fresh or frozen catfish fillets, about 1/2 inch thick; 1 teaspoon finely shredded lime peel; 3 tablespoons lime juice; 2 tablespoons snipped fresh cilantro; 2 tablespoons snipped fresh oregano; 2 tablespoons finely chopped green onion; 1 tablespoon olive oil; ¼ teaspoon salt; ¼ teaspoon cayenne pepper; 1 (15 ounce) can black beans, rinsed and drained; 1 medium avocado, halved, seeded, peeled, and diced; 1 medium tomato, chopped; Lime wedges