In a large heavy saucepan or enameled cast iron Dutch oven, sauté onions in butter over MEDIUM, stirring frequently, until they are translucent and begin taking on a slight golden color; about 8-10 minutes.Add the mushrooms and sauté 3-4 minutes more.
Reduce heat to LOW, and add the paprika, half of the fresh dill, wine, and soy sauce. Stir to mix, cover, and simmer 15 minutes, stirring occasionally.
Remove from heat, and add remaining butter to mushroom mixture. Stir to melt the butter. Sprinkle flour over mushroom mixture and stir to thicken.
Add half-&-half and stock all at once, stirring until smooth, and then season to taste. I usually add a little more paprika at this time.Turn the heat back to LOW-LOW, cover and simmer 10 minutes, then remove from heat.
(Optional) If you prefer a creamier soup, you can use an immersion blender at this time to smooth things out a bit. If you choose to blend the soup, don't go crazy: leave some larger, meaty pieces of mushroom or texture and bite.
Just before serving, stir in lemon juice and sour cream.Garnish with additional sour cream and chopped fresh dill.
Mushrooms: For a more complex mushroom profile, we recommend using a combination of mushrooms. Crimini, portobello, and white button mushrooms make an excellent combo.It isn't necessary, however, to have a bunch of different types of mushrooms; use what you can find. We often make this soup with exclusively crimini mushrooms with great results.Paprika: For Hungarian mushroom soup, a sweet, mild Hungarian paprika is the classic (and best) choice. Our favorite paprika to use when making this mushroom soup is a Hungarian Különleges paprika; a deep, bright red paprika with a very sweet flavor. (If you prefer your mushroom soup a little spicier, try this amazing Hungarian Sweet & Spicy Paprika!) When making Hungarian Mushroom soup, it is best to avoid using Spanish paprikas if possible. These are made from a slightly different type of pepper than Hungarian varieties, and in this case, its smoky flavor profile is not the paprika you're looking for.