For the dough, knead 200 g flour, baking powder, egg, sugar, 1 level teaspoon salt and butter in pieces, first with the dough hooks of the mixer and then briefly with your hands to form the dough. Chill for about 30 minutes.
Peel and cut the red beets into thirds. (Caution, they stain strongly, it is best to wear disposable gloves.) Heat 2 tablespoons of oil in an ovenproof pan (approx. 28 cm Ø). Fry the beetroots in it at medium heat for about 10 minutes.
Deglaze with 2 tbsp vinegar, honey and 50 ml water. Season well with salt and pepper. Bring to the boil, cover and stew for about 10 minutes.
Roll out the dough on a work surface floured with spelt flour and round (approx. 25 cm Ø). Prick several times with a fork. Pull the pan off the stove. Carefully place the dough on the beetroot and press the edge lightly.
Bake in a hot oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer) for about 25 minutes.
for the Salsa verde wash parsley and mint, shake dry and pluck leaves from the stalks. Peel the garlic. Finely chop and mix the herbs, capers and garlic. Stir in 1 tbsp vinegar and 1 tbsp oil.
Season with salt and pepper. Crumble the feta.
Remove the tart from the oven, carefully remove it from the edge and turn it over onto a plate. Serve with feta and salsa verde.