Ceviche Tostadas

Ingredients

• 8 5 1/2-inch extra-thin corn tortillas, or prepared tostada shells
• Vegetable oil for frying
• 1 pound orange roughy, red snapper or other fish fillet
• 1 1/4 cups Key lime juice, or 1 cup lime juice and 1/4 cup lemon juice
• 1 tablespoon salt
• 1/2 teaspoon dried oregano
• 2 heaping tablespoons cilantro, coarsely chopped
• 1/4 red onion, thinly sliced
• 1 medium tomato, diced
• Freshly ground black pepper to taste
• Hot sauce (optional)