Make a syrup by combining the finely diced lemon peel with the water & the sugar in a non-corrosive pan. Bring to a boil, reduce heat & simmer for 5 minutes. Remove from the heat & let cool. Combine the syrup with the lemon juice & the mineral water.
At this point, use one of two steps. Either use an ice cream maker & follow the maunfacturers instructions. Or, place in a tall canister & put in the freezer. Freeze for 1 1/2 hours. Remove, stir & beat briefly with a whisk. Return to the freezer & repeat the beating process after another 50 minutes. You may have to repeat this three or four times. The more you beat your sorbet, the more air is being incorporated & hence the lighter the finished product. Keep in the freezer above your fridge rather than a deep freeze otherwise you'll get a finished product that is hard. If you only have a deep freeze, place sorbet in fridge for 1 to 2 hours before serving.
Will keep for 3 or 4 days.
NOTE: The author from whom I adapted this recipe suggested that you do not use a deep freeze or any free standing when making sorbets because the temperatures are too cold. However, I have had no success making a sorbet from scratch in a fridge-freezer. I use my chest freezer & mix more often than is called for. When the sorbet is ready, then I transfer it to the fridge freezer for keeping it.
Adapted from Jim Tarantino, "Sorbets!"