Nesta's Lemon Curd

1 1/2 tsp cornflour
Juice and grated rind of 1 organic or unwaxed lemon
3 oz (85g) white caster sugar
2 1/2 oz (70g) soya margarine

1. Dissolve cornflour in a little of the juice.
2. Put rest of ingredients into saucepan and heat until sugar has dissolved. Gradually add this mixture to the cornflour mix, stirring well.
3. Return to the pan and boil until mixture coats the back of a spoon  not more than 1 minute. Put into a warmed jar and cover with greaseproof paper until cold.
4. Replace greaseproof with lid and store in fridge. Keeps well for over 3 weeks in fridge.