How to make a tomato and onion tart
Heat the oven to 200°C (180°C in a fan oven), gas 6.
Quickly knead the flour, butter, salt and the egg together to form a dough.
Wrap in clingfilm and allow to rest in the fridge for 30 minutes.
Mix the sour cream with the lemon juice and some salt and ground black pepper and then stir in the eggs.
Roll out the dough on a floured work surface approx. 1 cm thick and cut out a circle approx. 32 cm in diameter.
Place the dough in a cake tin lined with grease-proof paper so that there it has a 3 cm high edge.
Pierce the floor with a fork then spread the sour cream onto the dough and cover with the tomatoes.
Drag the onion rings through the olive oil and place on top of the tomatoes.
Bake the tart for approx. 30-40 minutes.
Before serving your tomato and onion tart, drizzle with basil oil.