In a large, heavy pot over medium-high heat, pour in the olive oil and add the sliced mushrooms. Season them with salt and pepper, cooking while stirring them until they achieve a golden brown color. Remove from heat and set aside.

Using the same pot, melt the butter and incorporate the ground beef. Cook it for about 5 to 6 minutes, until it's no longer pink. If using regular beef, ensure to drain off any excess fat.

Add chopped onions and minced garlic to the pot; sauté until softened while adding a pinch of salt and pepper. Stir in the flour and paprika, cooking for about a minute until the flour loses its raw flavor.

Pour the lemon juice and beef broth mixture into the pot, scraping the bottom to deglaze. Bring the mixture to a simmer before adding the beef broth.

Stir in the noodles and reserved mushrooms with their juices. Reduce the heat to medium-low, cover, and simmer while stirring occasionally until the noodles are cooked perfectly. Finally, remove from heat and stir in the sour cream before garnishing with parsley.