Cook green beans in salty water until they have a sligth bit. Strain the vegetable douse with cold water and drain well. Peel onion and dice finely.  Quarter tomatoes, remove seeds and cut them into small cubes. Spice vinegar with salt and peper, then add oil and blend thoroughly. Add beans, tomatoes and onions into a large bowl. Pour over the marinade and mix well. Let it sit for 20 minutes.
Warm up milk, add saffron and mix well. Cut across smoked trouts into 2 cm pieces. Prepare green salad and cut chive into small slices. Blend creme fraiche and saffron milk. Mix sauce and trout pieces carefully.
Place salad on 4 plates, then the vegetable and at last the mrinaded trouts. Garnish with chive.