Peel and finely chop the onion and possibly the garlic. Mix with vinegar, broth, mustard, salt, pepper and possibly sugar. Whip the oil into it
Clean and wash the tomatoes, lettuce and chicory (pluck lettuce finely). Cut the tomatoes into quarters or slices. Halve the chicory and cut off the stalk. Remove leaves and cut some of them into strips.
Arrange chicory leaves and strips, lettuce and tomatoes on plates. Drizzle the mustard marinade over them. Serve with baguette