In a large pot, melt the butter over medium heat. Add the chopped onion and sauté until translucent, about 5 minutes. Stir in the minced garlic and cook for an additional minute until fragrant.

Pour in the vegetable broth and bring to a boil. Add the diced potatoes and sliced carrots. Reduce the heat to a simmer and cook until the vegetables are tender, about 15-20 minutes.

Once the vegetables are cooked, stir in the chopped dill and heavy cream. Simmer for another 5 minutes, allowing the flavors to meld.

Season with salt, pepper, and lemon juice to taste. If desired, use an immersion blender to puree the soup for a creamier texture or leave it chunky for more texture.

Serve hot, garnished with additional dill if desired.