Heat some oil in a large cooking pot. Add leak rings and diced onion, fry it until golden and than add the chopped garlic. Keep frying for another minute and add chunks of mushrooms. While mushrooms are frying peel the carrot and potato and cut them into quarters. Chop the celery and add the vegetables to the pot. Add the spices and stir well. Cover with boiling water and add another cup. Cook until the carrot and the potato are tender. Turn off the heat and take out the carrot and the potatoes, mash them and put them back in the soup. To get a better texture process the soup or part of it in a food processor or with a blender.To get a thicker soup you can add some cream fresh or some roux.Serve hot and garnish with chopped dill, chili, sage or sour cream.