Roll out the pastry until it is 3 mm thick and prick with a fork. Cut a 15 cm circle and precook for 10 minutes at 140°C. Then leave to cool.
Peel and finely chop the onions and garlic cloves. Heat 20 ml of oil in a pan and brown the onions in thyme. As soon as they start to caramelise, add the anchovies and chopped garlic. Turn the heat right down and simmer for 5 minutes.
Wash and thinly slice the Annabelle potatoes using a mandolin.
Arrange the slices on a sheet of greaseproof paper in a 15 cm circle. Place the caramelised onion mix on top and cover with the pre-cooked pastry. Place in the oven for 15 minutes at 180°C.
Once cooked, turn the tart over and add the anchovy filets, crushed sea salt, olive oil and oregano.