Place the shrimp in a food processor and pulse until finely chopped (do not puree). Transfer the shrimp to a medium bowl. Mix in the mayonnaise, lime juice, cumin, Tabasco, green onions, cornstarch, salt and pepper and mix well to combine. Place the cornflake crumbs in a wide, shallow dish. Dampen your hands lightly with cold water and divide and shape the shrimp mixture into 8 balls. Set the balls on the cornflake crumbs. Sprinkle the top and sides with the crumbs and press and form the balls into 3-inch wide cakes. Heat the oil in a large non-stick skillet set over medium heat. Add the shrimp cakes and cook for 3 to 4 minutes per side, or until golden brown and well heated through. Serve 2 shrimp cakes per portion, garnished with lime slices, and, if desired, topped with salsa or tartar sauce.