01 - Bring the water or vegetable broth to a gentle boil in a large pot. Add the potatoes, carrots, and cauliflower. Simmer for 8 minutes until vegetables begin to soften.
02 - Add the green beans, peas, leek, and radishes if using. Cook for another 7 to 8 minutes until all vegetables are just tender. Avoid overcooking to maintain texture.
03 - Melt the butter in a small saucepan over medium heat. Stir in the flour and cook for 1 minute, stirring constantly to form a smooth roux without browning.
04 - Gradually whisk the milk into the roux, stirring constantly until the mixture thickens and becomes smooth. Continue whisking to prevent lumps from forming.
05 - Pour the milk mixture and cream into the soup pot. Stir gently to combine all ingredients. Heat through until steaming hot, but do not let the soup come to a rolling boil.
06 - Season with salt and white pepper to taste. Stir in the chopped fresh dill just before serving to preserve its delicate flavor.
07 - Taste the soup and adjust seasoning as needed. Serve hot in bowls, garnished with additional fresh dill sprigs if desired. Accompany with rye bread or crispbread.