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The natural blues and purples you get from fruit and grains have always intrigued me, and this tart stems from that curiosity.
You will need a round 23cm buttered tart tin with a removable base if possible.
160g cold butter
1/2 tsp salt
Few drops of vanilla essence
1 rounded tbs purple corn powder (try health food stores)
1 egg (and 1 tsp lemon juice if necessary)
● In a bowl or food processor, work the butter into the flour with the sugar, salt, vanilla and purple corn powder until the mixture resembles breadcrumbs. Add the egg and, if needed, lemon juice, and work the dough until it comes together smoothly. If it is too dry, add a little more lemon juice. Wrap in cling film and chill for 15 mins. On a floured work surface, roll out the dough in a circle large enough for your tart tin, about 5mm thick. Press into the tin, taking care to patch up any holes. Chill for 30 mins. Blind-bake for 25 mins at 180C. If the bottom centre is still soft, put back in the oven for a few minutes. Leave to cool.
250g blackberries (can be frozen)
3 tbs + 3 tbs sugar
3 eggs and 2 yolks
1-2 tbs apricot jam
● Put the blackberries, 3 tbs sugar and 1 tbs water in a saucepan. Add the zest of 3 lemons and cook slowly until the blackberries are soft. Press through a plastic strainer. You should get about 2/3 cup. Pour the juice into a metal bowl and add the other 3 tbs sugar, the juice of 3 lemons and the eggs and yolks. Whisk lightly. Place the bowl over a pan of simmering water and stir with a wooden spoon until quite thick. Take off the heat and add the butter, stirring constantly. Pour this curd into a container, cover and chill in the fridge. Spread the cold curd in the base of the tart. Place the blueberries in a saucepan with the apricot jam.
● Heat until they start to give out colour (about 3 mins) and become shiny. Pour over the curd. Chill the tart for a few minutes before slicing.
Rose Carrarini is co-owner of Rose Bakery in Paris and author of ‘Breakfast, Lunch, Tea’ (Phaidon, £19.95)