Melt 1 1/2 tablespoons butter in small saucepan over medium heat and whisk in flour. Cook roux, 2 minutes, stirring constantly. Add broth in slow stream, whisking constantly, and bring to boil. Reduce heat and simmer 3 minutes, whisking occasionally. Remove from heat and keep warm. Pat beef dry and season well with salt and pepper. Heat 1 tablespoon butter with 1 tablespoon oil in skillet over medium-high heat till foam subsides. Saute beef in 2 batches, 1 minute, turning once till browned on both sides but still pink inside. Transfer to plate with slotted spoon. Add remaining butter and oil to skillet and heat over medium-high heat till hot but not smoking. Saute shallot 3 minutes, stirring occasionally, till golden brown. Add mushrooms and saute 8-10 minutes, stirring occasionally, till liquid mushrooms give off is evaporated and mushrooms are browned. Return meat with its accumulated juices to skillet and stir to combine. Transfer to platter. Reheat sauce over low heat. Do not boil. Whisk in sour cream, mustard, dill, salt and pepper. Pour sauce over beef and serve immediately over egg noodles.