Frozen Berry Yoghurt

3 g agar agar
3 cups frozen berries
2 tsp lemon juice
¼ cup milk or ricemilk or soymilk
2 tbsp sugar
2/3 cup plain yoghurt

Dissolve agar in milk.
Whizz the berries and sugar.
Add the other ingredients.
Cover and freeze for one hour.
Whizz again and freeze for 4 hours.