In a small saucepan, combine the cranberries, lemon zest, and 1/2 cup / 120ml of the water.
Cook over medium heat for 5-6 minutes, stirring occasionally, until the cranberries pop and soften. Gently mash them with the back of a spoon.
Stir in the sugar, fresh lemon juice, and the remaining 1/4 cup / 60ml of water.
Bring the mixture to a boil, stirring until the sugar is completely dissolved.
Remove the saucepan from the heat and let the mixture cool completely to room temperature.
Pour the cooled mixture into a freezer-safe container and place it in the freezer for 30-45 minutes, or until it begins to freeze around the edges.
Transfer the semi-frozen mixture to a high-speed blender or food processor.
Blend until it's perfectly smooth and creamy.
Pour the blended sorbet back into the freezer-safe container.
Freeze until firm, at least 2-3 hours, before serving.
Adjust the sweetness to your liking.
Taste the mixture before freezing and add another teaspoon of sugar if your cranberries are particularly tart.
