1. Peel the onion and garlic. Roughly chop the onion, garlic, bell pepper, tomato and celery.
2. Place all ingredients, except seafood, in the bowl fitted with the ultrablade knife. Mix at speed 11 for 10 seconds or until desired consistency is reached.
3. In a large bowl, stir together seafood and dressing. Chill for at least 2 hours before serving.