Sorbet is the easiest thing an ice cream maker makes and the one where the recipe matters most, because there is no fat to hide behind. Fruit, sugar, water. Get the ratio right and it is superb; get it wrong and you have either a block of ice or a mixture that never firms up.
The sugar rule
Roughly 20 to 30 percent sugar by weight of the total mixture. Below that and there is not enough dissolved sugar to depress the freezing point, so it sets rock solid. Above it and the freezing point drops so far that it stays slushy and never firms up. This is a narrower window than in ice cream, where fat does part of the job.
The float test
A classical kitchen trick and a genuinely useful one. Float a whole, uncracked egg in the finished mixture. If a circle of shell about the size of a nickel shows above the surface, the sugar concentration is in the right range. Sinks means not enough sugar; sitting high means too much.
It works because sugar concentration changes the liquid's density, and density is exactly what determines how high the egg floats. Rinse the egg first and do not use it afterwards.
Why make a syrup instead of stirring sugar in
Because cold fruit purée will not dissolve a cup of granulated sugar. You will think it has, churn the batch, and end up with a gritty sorbet and a layer of sugar at the bottom of the container.
Five minutes of heat guarantees a solution. Cool it completely before combining, so you are not warming the purée and driving off its aromatics.
Acid and salt do more here than anywhere else
With no dairy to round things out, seasoning is the whole game. Lemon juice brightens fruit flavor that freezing dulls, and it is the difference between a sorbet that tastes of fruit and one that tastes of sugar. A pinch of salt does the same thing from the other direction.
Season the base so it tastes slightly too sweet and slightly too tart at room temperature. Cold suppresses both, so a base that tastes perfectly balanced warm will taste flat frozen.
The tablespoon of vodka
Optional and genuinely useful. Alcohol does not freeze at domestic freezer temperatures, so a small amount lowers the mixture's freezing point and keeps a lean sorbet scoopable rather than solid.
One tablespoon per quart is right. Much more and the sorbet will not set at all — this is why sorbets made with a lot of liqueur stay soupy.
Which fruit works
Excellent: raspberry, strawberry, blackberry, mango, peach, passion fruit, lemon, lime. Strong flavor and enough body.
Harder: melon and cucumber, which are extremely watery and give a thin result — reduce the water in the syrup. Banana and avocado, which are so thick they behave more like a dairy-free ice cream.
Best frozen: out of season, frozen fruit is usually better than fresh, because it was picked ripe. Thaw it and use the liquid.
Sorbet, sherbet and granita
Worth knowing since the words get used loosely. Sorbet has no dairy at all. Sherbet has a small amount of milk or cream, which makes it softer and paler. Granita is the same mixture frozen without churning and scraped with a fork, giving deliberate large crystals.
If your sorbet came out as accidental granita, the cause is almost always too little sugar — see why homemade ice cream is rock hard. And for the dairy-free route to something creamier, see the dairy-free guide.
