• Step 1: In a large non-reactive bowl (such as glass or stainless steel), combine the cubed fish and shrimp. Pour the fresh lime juice over the seafood, ensuring all pieces are fully submerged. Cover and refrigerate for 30-45 minutes, stirring occasionally, until the seafood is opaque and “cooked” through the acidity of the lime juice.
• Step 2: Drain any excess lime juice from the bowl, then add the sliced red onion, diced tomatoes, minced jalapeño (if using), and chopped cilantro. Gently toss to combine.
• Step 3: Just before serving, fold in the diced avocado. Season the ceviche with salt and pepper to taste.
• Step 4: Serve the authentic ceviche immediately, accompanied by tostadas, crackers, or tortilla chips. Enjoy the bright, refreshing flavors of this delightful seafood dish.