
For the pastry:
150g plain flour
75g butter
1 tbsp icing sugar
water to mix
rub the butter into the flour until it resembles bread crumbs. Sprinkle in the icing sugar then add water to form a soft pastry. Grease a 22cm round loose-bottomed tart/flan tin and line with the pastry. Cover with grease-proof paper, fill with baking beans and blind bake at 180c for about 15 minutes. Remove the beans and paper, and bake for a further 10 minutes or so until the pastry is cooked and golden brown.
I always line the tin with the pastry but don't trim until after it has blind baked for 15 minutes. I find if you trim with a bread knife you end up with a nice clean finish.
For the lemon filing:

1 lemon (juice and zest)
15g cornflour
1 egg yolk
small knob of butter
55g caster sugar
Put the cornflour in a jug with a couple of spoonfulls of water. Bring the remainder of the water to the boil with lemon zest and pour this over the cornflour. Pour the mixture back into the saucepan, add the lemon juice and boil until thick. Add the sugar and butter and beat until smooth. When the mixture has cooled down slightly, beat in the egg yolk. Pour this into the cooked pastry case.
Once the lemon filing has set, arrange the blackberries on top then prepare the blackberry jelly.
For the blackberry jelly:
About 100g blackberries (I used the squashy and small ones that were leftover)
enough water to just stop the blackberries from burning
a table spoon of sugar
6g gelatine

Serve with a cup of tea and a sunny day