1. Combine first 5 ingredients in a small bowl. Heat a large nonstick skillet over medium-high heat. Combine shrimp and Cajun seasoning in a bowl; toss well. Add olive oil to pan, and swirl to coat. Add shrimp to pan; cook 2 minutes on each side or until done.
2. Cut each roll in half horizontally. Top bottom half of each roll with 2 tablespoons lettuce, 2 tomato slices, 1 onion slice, and one quarter of shrimp. Spread top half of each roll with about 2 tablespoons mayonnaise mixture; place on top of sandwich.
Carrot and cabbage slaw: Combine 4 cups shredded green cabbage and 1 cup shredded carrot in a large bowl. Combine 3 tablespoons reduced-fat mayonnaise, 1 tablespoon cider vinegar, and 1/4 teaspoon celery seeds in a small bowl. Add mayonnaise mixture to cabbage mixture; stir well.
Using salt-free Cajun seasoning reduces the sodium in this dish without sacrificing any of the flavor. Carrot and cabbage slaw makes for a crunchy side dish.