Peel and finely chop the onion. Finely dice the sausage or ham and cucumber. Mix vinegar, salt, pepper and sugar. Whip oil into it. Mix onion, sausage and cucumber with the marinade. Leave to stand briefly. Wash parsley and chop finely except for a little bit
Mix cream yoghurt and crème fraiche. Season with salt and pepper. Put some yoghurt cream on each baguette slice. Arrange the sausage salad on top. Garnish with parsley, lettuce leaves and tomatoes as desired
You can prepare the topping very well - it tastes best when well-done. However, do not spread it on the baguette until shortly before serving. If you like, you can roast it briefly before serving