1. Sift together the flour, salt and xanthan gum.

2. Rub in the sunflower spread to make a breadcrumb consistency.

3. Mix in the egg yolk and sugar.

4. With a round ended knife, gradually mix in the water until you reach a nice doughy consistency. You might need more or less than the 2 tbsp specified.

5. Wrap in cling film and chill in the fridge for 15 mins, once chilled roll out and press into a greased 10 inch flan dish

6. Place a sheet of grease proof paper inside the pastry and add either baking beans or rice on top and blind bake on gas mark 4 for about 20 mins until the pastry is cooked.

7. Once cooked remove the grease proof and beans and set pastry case aside and allow to cool.

8. Meanwhile, put the cornflour, lemon zest and sugar in a pan and gradually mix in the lemon juice.

9. Add some water to the orange juice to make up to 200ml and add to the lemon mix.

10. Place the pan on a medium heat continuously stirring until thickened. Once the mix has thickened stop stirring and let the mixture start to bubble. As soon as it starts bubbling remove from the heat.

11. While off the heat beat in the butter then stir in the egg yolks and egg.

12. Place back on the heat, keep stirring until the mixture thickens further, once the mixture reaches the stage where it \\\"plops\\\" off the spoon remove from the heat and pour into the pastry case and allow to cool.

13. Once the filling is cold, place the egg whites in a bowl and mix with an electric whisk for a few minutes until fluffy but not too thick, gradually pour in the sugar while still whisking, the mix will go shiny and very thick, once you get stiff peaks spread over the top of the lemon and brown with a blow torch (if you don\\\'t have a blow torch place under grill for a few minutes)