Simmer sugar and water in a small heavy saucepan, stirring, until sugar is dissolved, then remove from heat.

Crush vitamin C tablet to a powder with a mortar and pestle or the back of a spoon and place in a 1-quart container that will fit under spout of juicer.

Using electric juicer, juice apples into container. Spoon off foam and stir in sugar syrup. Chill, covered, until cold, at least 1 hour.

Freeze in ice-cream maker.

Cooks notes:

. Its not necessary to peel or seed the apples before putting them in the juicer.

. Sorbet can be kept, frozen, in an airtight container 1 week.