If using fresh beetroot, put them in a large saucepan of water and bring to the boil. Cook for 30–40 minutes (depending on the size of the beetroot) until soft. Rinse in cold water. The peel will come off easily when you rub them with your fingers. Set aside.

To make the pastry, cube the butter and crumble it with the flours and salt. This is quickly done in a food processor. Add the egg yolk and water and quickly, without working the dough too much, shape into a ball. Leave to chill in the fridge or freezer for 30 minutes before using.

Roll out the dough and carefully place into the fluted loose-based pie tin. Prick the bottom of the case with a fork in several places. Leave to rest for another 15 minutes in the fridge or freezer.

Preheat the oven to 180°C (350°F) Gas 4. Pre-bake the crust in the middle of the preheated oven for around 10 minutes. Meanwhile, mix the crème fraîche/sour cream, milk, eggs, crumbled feta, salt, pepper and half the dill in a bowl. Cut the fennel lengthways and remove the bottom core. Thinly slice the fennel.

In a saucepan, add a little oil and sauté the fennel on a low heat for 5–6 minutes. After a few minutes, add a few teaspoons of balsamic vinegar. Remove the crust from the oven. Scatter the sautéed fennel across the base and add one-third of the crème fraîche/sour cream mixture.

Thinly slice the beetroot and arrange the thin slices all across the tart in neat layers. Add the remaining crème fraîche/sour cream dressing on top and scatter with half of the crushed walnuts. Return to the middle of the oven for around 20–25 minutes. When done, scatter the remaining dill and walnuts on top. Serve warm.