If the broth is frozen, thaw it now.
Heat the Dutch Oven / soup pot to medium on the stovetop.
Melt a tablespoon of butter in the pot. Add diced onion and a tiny pinch of salt.
Cook onion, stirring occasionally, for about 10 minutes until the onion turns translucent and starts to brown. (If the onions are browning too quickly, reduce the heat)
Add diced carrots to the pot. Cook for 5 minutes, stirring a few times.
Add diced potatoes and stir. Cook for 5 minutes, stirring a few times.
Add the broth to the pot. Stir.
Bring to a simmer, then reduce the heat to medium-low.
Cover the pot with a lid and cook for 20 minutes, until the potatoes soften.
Ladle 1/2 cup of hot soup into a bowl, and add in the milk. Blend together and return to the cooking pot.
Add chopped dill, lemon juice, salt, pepper, and nutmeg. Cook for another 5 to 10 minutes on medium-low to let the flavors blend.
Serve hot.