Melt butter in a large pot or Dutch oven over medium heat. Add the chopped onion and cook until softened about 2 minutes.
Add sliced mushrooms and minced garlic to the pot. Cook until the mushrooms release their liquid and start to brown, about 8-10 minutes.
Stir in the dried dill weed, paprika, pinch of salt and fresh thyme leaves. Cook for another minute.
Pour in the vegetable broth, soy sauce and lemon juice and let it simmer for 5 minutes.
In a separate bowl, whisk together the milk and flour until smooth. Slowly pour this mixture into the pot, stirring constantly to prevent lumps from forming.
Let it cook for about 10-15 minutes, stirring occasionally, until slightly thickened.
Taste the soup and adjust the seasoning with salt and pepper as needed.
If using sour cream, you can either add it directly to the soup and stir until well combined, or you can dollop it on top of each bowl when serving.
Serve the Hungarian Mushroom Soup with crusty bread or baguette, garnished with fresh chopped parsley. Enjoy!
