Bring the vegetable stock to the boil in a saucepan and add the diced potatoes. Dice the onion very small.
Crumble the tartare and stir into the saucepan with the onion cubes. Peel the cucumber, cut into small cubes and add to the saucepan. Simmer on a low flame for about 5-10 minutes until the cucumber and potato are soft. Remove the pan from the heat, stir in the chopped dill & sour cream and season with spices.