Cut the mango; mark lengthwise then crosswise and scoop out the pulp with a spoon.
Blend the pulp then add the lime juice. Add the sugar and blend until the sugar is dissolved.
Place in a metal baking pan and cover with foil. Freeze until firm (about 3 hours). Alternatively, you can freeze in an ice cream maker according to manufacturer's instructions.
Let the sorbet soften at room temperature before serving. If you don't have an ice cream maker, freeze the mango until firm (about 3 hours) then take a fork and mash the sorbet, then freeze until firm again before serving.