Thinly slice the mango, slicing from the 2 wider sides of the fruit, to make 8 thin slices. Cut 8 circles using a 3-inch round cookie cutter and finely dice remaining mango; set aside. Stir together lime juice, fish sauce and sugar in a small bowl; stir to dissolve sugar. Add red pepper flakes, onion and herbs. Gently stir in the diced mango, crabmeat, coconut milk and coconut. Cover and refrigerate for 30 minutes. To arrange salad, set a 3-inch ring mold or springform pan on a salad plate. Place a mango slice on the bottom then fill with crabmeat salad. Carefully press down on the mixture to pack into mold, letting some of the juices run onto the plate. Top with another mango slice then carefully remove mold. Repeat with remaining mango and salad. Makes 4 servings.