Clean the salad, wash thoroughly and drain. Wash the meat, dab dry and cut into finger-thick strips. Season with salt and pepper. Heat 2 tablespoons of oil in a pan in portions.
Brown the meat in 2 portions on each side for 2-3 minutes. Place the fried meat on one half of a baking tray. Wash the thyme, dab dry and remove coarse stalks. Stir cheese, thyme and cream with the whisk of the hand mixer until smooth.
Spread the cheese on the meat. Put walnuts on the other half of the baking tray. Gratinate the meat under the preheated grill of the oven for 3-4 minutes. Cover the nuts at the end if necessary. In the meantime peel onions and cut them into rings.
Take the meat out and let it cool down. In the meantime season vinegar with salt, pepper and sugar. Stir in mustard and add 4 tablespoons of oil. Mix walnuts, onions, vinaigrette and salad.
Arrange salad and meat on plates. Serve with toasted baguette sprinkled with olive oil and seasoned with salt and pepper.