Cóctel de Camarónes aka Mexican Shrimp Cocktail

Ingredients

• Salt and pepper to taste
• ¼ red onion, diced
• 1 pound peeled, deveined and cooked jumbo shrimp, halved crosswise
• ½ seedless cucumber, chopped
• ¾ cup fresh corn kernels (from 1 cob of corn)
• 2 ½ cups tomato juice (can use a mix of clam juice and tomato juice if preferred)
• ½ cup fresh lime juice (from about 3 limes)
• 1 large avocado, peeled, seeded and chopped
• queso fresco for garnish
• saltine crackers for serving