In a medium saucepan, combine water and sugar. Heat over medium heat, stirring until the sugar is completely dissolved. Remove from heat and let cool to room temperature.
Blend the diced mangoes in a blender or food processor until smooth.
In a large mixing bowl, combine the mango puree, cooled sugar syrup, lime juice, chili powder, and a pinch of salt. Mix thoroughly to ensure the chili is evenly distributed.
Taste the mixture and adjust the sweetness or heat by adding more sugar or chili powder if desired.
Pour the mixture into a shallow dish or an ice cream maker if you have one.
If using a shallow dish, place it in the freezer. Every 30 minutes, stir the mixture with a fork for about 3 hours until it reaches the desired sorbet consistency.
If using an ice cream maker, churn according to the manufacturer's instructions until it reaches a soft-serve consistency, then transfer to a freezer-safe container to harden for at least 2 hours.
Before serving, let the sorbet sit at room temperature for a few minutes to soften slightly.
Notes
Serve in chilled bowls or glasses, garnished with fresh mango and chili powder.