Heat olive oil in a large pot, then add chopped onion and cook until softened. Add minced garlic and cook for another minute until fragrant.

Add sliced mushrooms to the pot and cook until they release their liquid and start to brown.

Stir in Hungarian paprika and dried marjoram, cooking for a minute until fragrant.

Sprinkle flour over the mushrooms and stir well, cooking for 1-2 minutes to toast the flour.

Gradually whisk in vegetable broth, bringing the mixture to a simmer. Cook until the soup thickens slightly.

In a separate bowl, whisk together sour cream and milk. Slowly whisk a ladleful of the hot soup into the cream mixture to temper it, then pour the tempered cream back into the pot, stirring constantly.

Heat through gently, without boiling. Stir in fresh dill and season with salt and black pepper to taste.