Chilled Shrimp Pasta Salad

Ingredients

• 3 cups uncooked small pasta shells
• 1/2 cup sour cream
• 1/2 cup mayonnaise
• 1/4 cup horseradish sauce
• 2 tablespoons grated onion
• 1-1/2 teaspoons seasoned salt
• 3/4 teaspoon pepper
• 1 pound peeled and deveined cooked small shrimp
• 1 large cucumber, seeded and chopped
• 3 celery ribs, thinly sliced
• Red lettuce leaves, optional