Mushrooms with Sour Cream Sauce -

Name: Mushrooms with Sour Cream Sauce -
Cuisine: World Cuisine, European
Ingredients: 1 lb. fresh mushrooms, I suggest baby portabella mushrooms for this recipe (or wild frozen mushrooms, I found them in Russian supermarket); 1 Tbsp. butter; 1 Tbsp. olive oil; 1 medium onion, peeled and diced; 3 garlic cloves, finely chopped; salt, and freshly ground pepper; 1 Tbsp. all-purpose flour (or whole wheat flour); 3/4 cup sour cream; shredded cheese; chopped fresh dill to serve