Start to boil the potatoes until they're soft boiled.
Pass the boiled potatoes throgh a potato ricer or a meat grinder and let them cool. Preheat the oven to 200 degrees Celcius or 390 degrees Fahrenheit.
Mix the dried tomatoes with their oil in a mixer until you get a smooth tomato paste.
Mix the potato puree with the tomato paste, salt and flour. Knead the dough and divide it in 4 balls. Roll every ball out to a long snake with the caliber of 2 cm. Cut 2 cm long pieces out of the snake and place them on a baking sheet. Bake them in the oven for 20 - 30 minutes until light brown and supercrisy.
Wash all the vegetables and cut them into 0,8 cm cubes and the leek in thin slices.
Start to sauté the leek in a saucepan on high heat with some olive oil. After 1 minute throw in the other vegetables, season them with salt and pepper and sauté for another 3 minutes.
Add the tomato paste and deglace the vegetables with the white wine. Let the vegetables roast for 5 minutes and if necessary, add a splash of water or vegetable broth.
Mix all the ingredients of the yoghurt sauce.
Take the gnocchi out of the oven and plate them with the vegetable ragout, the yoghurt sauce and some chopped chives.