Peel and cut up the mango into chunks. Puree the mango and 2 tablespoons of lime juice in a blender; set aside.
In a small heatproof bowl, mix the gelatin into the remaining 3 tablespoons of lime juice. Place the bowl in a small saucepan of simmering water and stir until the gelatin dissolves.
Add the gelatin-lime juice mix to the mango puree.
Whisk the egg whites to soft peaks. Add sugar or Splenda.
Gently fold the egg whites into the mango.
Place the mixture into a freezer-proof bowl for about 2 hours. Then take the bowl out of the freezer and mix to break up the ice chunks and return to the freezer. Allow it to freeze until firm or solid.
If the sorbet is frozen solid prior
to serving, place in the refrigerator for about 10 minutes before serving.
Scoop the sorbet into bowls and garnish with lime zest strips.