If necessary, remove the outer leaves from the chicory, following carefully cut out the bitter core wedge-like with a sharp kitchen knife, rinse the chicory.
Steam in a little water, to which you have added salt and juice of one lemon, in about 10 minutes until soft. Next, remove the chicory from the liquid, the cooking liquid is used for the cheese sauce, but it should not be more than 0, 1 5 l.
Make a roux with butter and flour, add milk and beef broth and cook until it becomes creamy. Then add the liquid from the chicory, the sour cream, the grated cheese and maybe a little salt.
Place the chicory in an ovenproof dish, pour the cheese sauce over it and sprinkle with the remaining cheese. Cut the tomatoes into slices, you can put them on before or after grilling.
Brown briefly under the heated broiler, the cheese should melt well, but in any case not turn black.
To serve: Garnish with parsley, this dish is served as an entrée or as a light main course.