In a large pot, heat 2 tablespoons of olive oil over medium heat until shimmering. Add 2 cups of diced yellow onions and 1½ pounds of sliced mixed mushrooms. Sauté for about 15 minutes, stirring occasionally, until the onions are translucent and the mushrooms have softened.

Once the vegetables are ready, add 3 tablespoons of unsalted butter to the pot. Let it melt, then whisk in ¼ cup of all-purpose flour along with 4 teaspoons of sweet mild paprika and 1 tablespoon of fresh dill. Cook for about 1 minute to create a roux.

Pour in ½ cup of dry white wine to deglaze the pot, scraping up any flavorful bits. Whisk until the wine has evaporated. Gradually incorporate 3 cups of broth, stirring to dissolve the flour mixture. The soup should begin to thicken slightly.

Stir in 2 tablespoons of low-sodium soy sauce and the sautéed mushroom mixture. Bring to a gentle simmer and cook for about 5 minutes to deepen flavors.

Reduce heat to low and whisk in 1½ cups of whole milk and ¾ cup of sour cream until combined. Warm gently without boiling. Adjust seasoning with kosher salt and black pepper.

Just before serving, stir in 2 tablespoons of white wine or sherry vinegar. Serve hot, garnished with fresh parsley and dill.