Prepare the simple sugar syrup by mixing water and sugar (by heating it, or simply by shaking it). Let cool down.
Cut the melon, remove the seeds and purée the fruit, together with the 50 gram of sugar.
Mix together the sugar syrup and the fruit purée. If you want to make sure that you have the appropriate level of sweetness for sorbet, do the Egg test.
Take about 100 ml (about 0.4 cup) of the mixture, heat to about 40° Celsius (104 °F) and quickly whisk in about 2 grams of Agar agar.
When well dissolved, pour back into the rest of the mixture, whisk well and churn in your ice cream machine according to its instructions.
In case you worry that the sorbet might become too sweet for you, add lemon juice from about ½ lemon (according to your taste) to the base before churning it.