Wash the potatoes and cook in boiling salted water for about 20 minutes. Clean, wash and peel the carrots and cook them in boiling salted water for about 8 minutes. Clean, wash and finely dice the zucchini.
Wash, clean and slice the tomatoes. Halve the avocado and remove the stone. Peel the avocado and cut into slices. Wash the cress and cut it from the bed. Peel the potatoes and mash them with a fork.
Add stock and vinegar to the potatoes and mix. Season with salt, pepper, cress and sugar and add oil. Arrange the vegetables on a plate and add some potato vinaigrette.
Sprinkle the zucchini cubes on top and serve the salad plate sprinkled with parsley and coloured pepper. Add the rest of the potato vinaigrette separately.