Wash the potatoes and cook in boiling water for about 20 minutes. Then rinse with cold water and let cool down. In the meantime, cook the snow peas in boiling salted water for about 5 minutes. Quarter tomatoes. Drain the sugar snap peas well.
For the curry cream, mix the mayonnaise, yoghurt and vinegar together. Season to taste with salt, pepper, sugar and curry. Peel the potatoes. Mix with snow peas and tomatoes. Fold in the curry cream. Chop the parsley and sprinkle over it.