To prepare the zucchini, cut into half lengthways, then across into 1 centimeter / 1/2 inch slices. Simmer the zucchini pieces in water until cooked to liking. They should be soft, but not mushy. Meanwhile, mix the sugar and salt into the vinegar until completely dissolved. When the zucchini is cooked, drain and cool to room temperature. Add the sweet vinegar just before serving, and mix well.

You can eat this dish hot, but I think it's nicest at room temperature. It will keep for a few hours, but it's best to add the vinegar immediately before serving.