In 2 quart saucepan, combine tomato soup, pineapple, mushrooms, garlic powder and brown sugar. Cook 15 minutes over moderate heat stirring frequently.
Add cooked shrimp and crawfish, then simmer for 5 minutes. Cool until lukewarm.
While cooling, arrange shredded lettuce in 6 salad bowls and top with equal amounts of onion, celery and green pepper. Add equal amounts of lukewarm cooked mixture over lettuce, etc. and garnish with tomatoes. Salt and pepper (preferably fresh ground peppercorn) to taste.
Cajun Country -- New Iberia, Louisiana