Prepare all the vegetables. Cut the winter vegeables into thin slices, cutting the slices in halves or quarters when large. Break the cauliflower into sprigs. Leave most of the summer vegetables whole, cutting the carrots in thick slices, if not really small, trimming the spring onions rather short and cutting the tomatoes into wedges. Melt the fat in a saucepan. Add the vegetables to it at intervals, starting with the ones which take the longest time to cook. Put the lid on the pan after each addition and toss the vegetables in the fat. (Do not add the tomatoes to the summer vegetables until 5 min. before serving.) Add the liquid and the salt (use very little water with the summer vegetables), and simmer gently until the vegetables are tender. Serve hot, sprinkled with chopped parsley.