Authentic Mexican Shrimp Cocktail (Coctel de Camarones estilo Mexicano)

INGREDIENTS

• 1/3 cup Spanish onion, chopped
• 1/4 cup freshly squeezed lime juice
• 1 pound chilled cooked medium shrimp - peeled, deveined, and tails removed
• 2 roma (plum) tomatoes, chopped
• 1 cucumber, finely chopped
• 1 stalk celery, finely chopped
• 1 jalapeno pepper, seeded and finely chopped
• 2 teaspoons salt
• 2 teaspoons ground black pepper
• 1 1/2 cups chilled tomato and clam juice cocktail (such as Clamato®)
• 1 cup chilled ketchup (such as Heinz®)
• 1 bunch fresh cilantro - stems discarded and leaves chopped
• 2 tablespoons hot pepper sauce (such as Valentina®)
• 2 avocados - peeled, pitted, and chopped