Add the skewers and turn to coat the shrimp. Set aside. In a medium bowl, combine the onion with the remaining 1/4 cup oil and 1/4 teaspoon salt, the parsley, sage, vinegar, and pepper.

1 pound raw medium shrimp, peeled and deveined, shells reserved. 3 cups water. 1 1/2 pounds skinless catfish or cod fillets (halve fillets lengthwise if large), cut crosswise into 1-inch strips ...