Preheat oven to 450°.
Melt margarine in a large nonstick skillet over medium heat. Add celery, bell pepper, and jalapeño; sauté 3 minutes or until tender. Cool.
Combine mayonnaise and the next 5 ingredients (mayonnaise through egg) in a large bowl. Add celery mixture, breadcrumbs, green onions, crabmeat, and corn, and stir well. Divide crabmeat mixture into 10 equal portions, shaping each into a 1/2-inch-thick patty. Dredge patties in cornflakes.
Place patties on a baking sheet coated with cooking spray. Bake at 450° for 15 minutes; turn patties over, and bake an additional 10 minutes or until golden. Serve crab cakes with cocktail sauce, and garnish with cilantro sprigs, if desired.