Weigh the flour in a large bowl, or the bowl of a stand mixer. Add 1½ tsp salt, the sugar and the yeast and stir to combine. Pour in 200ml warm water and the oil and mix until you form a soft dough – it might feel a little sticky but don’t be tempted to add more flour until it’s been kneaded. Knead for 10 mins by hand, or 5-7 mins in a mixer (the dough will be less sticky and bouncier when it’s ready). Put it back in a clean, oiled bowl, cover with a tea towel and set aside to rise for an hour or two (depending on the temperature in the kitchen).

Heat the olive oil in a large frying pan or casserole dish. Add a good splash of the oil from one of the jars of anchovies too. Add the fennel, sugar, vinegar, fennel seeds and a splash of water and cover the dish with a lid. Cook over a low heat for 10 mins, remove the lid and continue to cook, stirring every so often, until it’s really soft and caramelised. This can take up to 30 mins so be patient. Remove from the heat and leave to cool.

Cook the potatoes in a pan of boiling water for 2-3 mins. You want them to just start softening, but not cook all the way through. Drain and leave to steam-dry in the colander.

When the dough has doubled in size, tip it onto your work surface and give it a few kneads and folds to knock out some air. Oil a large roasting tin (ours was 24cm x 38cm) and roll the dough out to almost fill it, leaving a little space for it to rise. Spread the cooked fennel over the dough, leaving a little border around the edge. Arrange the anchovy fillets in a diamond pattern on top, then fill the spaces with overlapping slices of potato and lemon. Sprinkle the potatoes and lemon with some sea salt and the whole tart with black pepper, then drizzle generously with the remaining oil from one of the anchovy jars. Cover lightly with cling film and leave to rise for another 30 mins to 1 hr until the dough has puffed up and filled the tin. Heat oven to 220C/200C fan/gas 7.

If you gently press the dough and it doesn’t bounce back, it’s ready. Bake for 25-30 mins. Serve warm, cold or reheated, cut into squares.