Preheat the oven to 200 degrees. Cut the zucchini without seeds into thin slices, add finely chopped onion and grated garlic. Mix, add the vinegar, purée, oil, sugar, a pinch of pepper and salt and worcestershire sauce.
Pour the well mixed mixture into the baking dish and bake in the preheated oven for about 45 minutes. Stir several times during baking. Let the finished mixture partially cool and serve. Or store it in a sealed jar in the refrigerator for further use.