Agar

Agar is a setting agent made from red seaweed; agar-agar is another name for it. It is sold as powder, flakes, strips or dried seaweed, and the forms are not interchangeable spoon for spoon.

Whisk the powder into a cold liquid, bring it to a full boil and simmer for about 2 minutes, stirring; agar needs boiling to dissolve and set. Pour it into moulds before it cools, as it begins setting at room temperature.

Yes, but agar sets more firmly and can set at room temperature, so use less and expect a different texture. A useful starting point is about 1 teaspoon of agar powder for 500 ml of liquid; boil it to activate, then adjust the amount next time if needed.

The agar may not have been boiled long enough to dissolve, or there may not have been enough for the amount of liquid. Bring the mixture back to a boil, whisk in a little more powder, simmer for 1–2 minutes and let it cool again.

Freezing often damages agar’s firm gel, so the dessert may release water and become grainy after thawing. Keep it covered in the fridge instead; the set texture is usually best within a few days.

Use it for fruit jellies, panna cotta-style puddings, vegan cheesecakes and clear layers in desserts. In Japanese cooking, kanten desserts are made with agar, often served with fruit or sweet bean paste.

Agar is exceptionally high in fibre: 81 g per 100 g, and it is also high in calcium, magnesium, iron and zinc. A serving uses only a small amount, so it contributes far less than the per-100 g figures suggest.

Agar sold for cooking is intended to be eaten when prepared as directed. Avoid swallowing dry powder or strips, which can swell after absorbing liquid; use the stated amount and dissolve it fully before serving.