Sardinesare high in omega-3 fatty acids, whichhelp prevent arrhythmias associated withheart attacks; the pickled fish canbe served as a first course or side dish.
Stir carrots, celery, onion, and oregano in a bowl. Transfer half the mixture to a 7 1/2-by-9 1/2-inch glass baking dish. Sprinkle with 1/2 teaspoon salt; season with pepper.
Lay sardines, skin side up, over vegetable mixture in dish. Top with remaining vegetable mixture. Sprinkle with remaining 1/2 teaspoon salt, and season with pepper. Stir vinegar, sugar, and 1 cup water in a medium bowl until sugar has dissolved. Drizzle over sardines and vegetables. Cover, and refrigerate until sardines are opaque and slightly firm, about 1 1/2 hours. Drain. Drizzle sardines and vegetables with oil, and gently toss. Transfer to a platter.