Wash the potatoes and cook for 15-20 minutes in boiling water. Then rinse with cold water, peel and leave to rest. In the meantime peel onions and cut them into fine rings. Wash the tomatoes and possibly cut them in half. Clean and wash radishes and cut into fine slices. Cut potatoes into slices. Dice bacon finely, leave out crispy, take out.
Heat vinegar and broth in bacon fat. Season with salt, pepper and sugar. Add onion rings briefly, then pour over the potatoes. Leave to stand for about 30 minutes. Slice the parmesan. Wash the basil and pluck the leaves. Mix all prepared ingredients and oil carefully with the potatoes, season again