Microwave broth and porcini mushrooms until softened. Strain and chop mushrooms.
Brown onions and tomato paste in oil. Stir in wine, soy sauce, broth, porcini, and mushroom liquid. Bring to boil.
Transfer to slow cooker with beef and mushrooms. Cook 6 to 7 hours on high or 9 to 10 hours on low.
Whisk flour with some sauce. Stir back in. Cook until thickened, about 15 minutes.
Stir in sour cream and dill. Season and serve over egg noodles.