Arrange potatoes in a single layer on a microwave-safe dish. Sprinkle with garlic salt and black pepper. Microwave on high for 15 minutes or until potatoes are tender.
In a large mixing bowl, combine potatoes, shrimp and 1 tablespoon vinaigrette; toss gently to combine.
Add remaining vinaigrette, spinach, bell pepper, red onion, cheese and black olives.