Combine cubed mango, orange juice, lime juice, and tequila in a food processor; process until smooth. Pour the mixture into a bowl, and stir in the agave nectar and 1/3 cup water. Cover and chill for 2 hours.
Pour mixture into the freezer can of an ice-cream freezer; freeze according to manufacturer's instructions. Spoon sorbet into a freezer-safe container; cover and freeze 8 hours or until firm.