Lemon sorbet with basil

Pour some boiling water over the lemons and oranges and scrub them clean. Use a vegetable peeling knife to remove a thin layer of zest from the citrus fruits. Bring the water to a boil, add the citrus zest and sugar. Stir until the sugar has melted and simmer for 10 more minutes over low heat. Remove from the stove and let the syrup cool completely. Squeeze the juice out of the oranges and lemons, add cool syrup and chopped basil. Stir and pour the mixture into an ice cream machine. Let the ice cream machine churn the mixture into a cold treat and keep it in a freezer for a few hours. To prepare the sorbet without an ice cream machine, pour the mixture into a wide box and place it in the freezer. Stir the mixture with a mixer or a fork once every half hour. Allow the mixture to freeze through.