How to Make It
Preheat broiler with oven rack 6 inches from heat. Place bread on a wire rack on a baking sheet; broil until golden brown, about 3 minutes. Remove pan; set aside.
Gently combine crabmeat, mayonnaise, cilantro, basil, lime zest, salt, chili powder, and cayenne in a large bowl.
Spread crab mixture evenly over bread slices. Top evenly with tomato slices and cheese. Return pan to oven, and broil until cheese is melted and starting to brown, about 3 minutes. Let cool 5 minutes, and serve immediately. Top with basil.