Peel and wash the potatoes and cook in salted water for about 20 minutes. Clean and wash the vegetables. Cut carrots into thin diagonal slices, celery or leek into pieces
Heat the oil. Sauté the vegetables briefly in it. Deglaze with 4-6 tablespoons of water, bring to the boil. Stir in stock. Cover and steam for 6-8 minutes
Add milk, bring to the boil. Grate cheese and melt. Season sauce with salt and pepper. Arrange everything and garnish with parsley if necessary