Wash the potatoes thoroughly. Cook in boiling water for about 20 minutes. Peel onion and dice coarsely. Peel garlic and chop finely. Wash parsley, dab dry and cut into strips. Drain the potatoes, rinse and rinse with cold water, peel and let cool down a little. Then cut into slices.
In the meantime mix vinegar, salt, pepper, sugar and garlic. Fold in the oil. Mix potatoes, onion, olives and parsley. Drizzle with vinaigrette and mix in. Let the salad stand for about 1 hour. Serve garnished with parsley as desired