Braising is an excellent way to tenderize an inexpensive cut of meat like top round—and create a rich-tasting sauce. Embellished with mushrooms, colorful bell peppers and a dollop of low-fat sour cream, it becomes downright luxurious. Try serving this over barley instead or whole-wheat egg noodles.
Slice beef across the grain into thin strips. Heat 1 teaspoon oil in a Dutch oven over high heat. Add beef and cook until browned on all sides, 1 to 2 minutes. Transfer to a plate. Reduce heat to medium.
Add 1 teaspoon oil to the pot. Add onion and cook, stirring, until golden, about 5 minutes. Add garlic, flour and paprika; cook, stirring, for 1 minute more. Add broth, mustard and the reserved beef. Bring to a simmer, cover the pot and transfer to the oven. Bake the stroganoff until the beef is very tender, 1 to 1 1/2 hours.
Meanwhile, heat the remaining 1 teaspoon oil in a large skillet over high heat. Add bell peppers and cook, stirring, about 1 minute. Add mushrooms and cook, stirring, until the mushroom liquid has evaporated, about 5 minutes. Season with salt and pepper.
Add the vegetables and sour cream to the stroganoff; stir to combine. Season with salt and pepper and garnish with parsley.