Wash the chard, remove the stalk and cut the leaves into strips. Wash the zucchini and cut into slices. Peel the onion and cut into cubes. Sear the onion and zucchini until they have toasted aromas.
For the dressing, stir the ingredients together and season the sauce to taste if necessary. Place the chard, zucchini, onions and dressing on plates or in bowls.