Sear. In a Dutch oven on medium-high heat, heat your olive oil for one minute. Then brown your beef until it is seared on all sides. Once seared, you can use a slotted spoon to remove the beef from the Dutch oven and set it aside while you work.
Saute. Add the onion, garlic, and mushrooms to the oven and saute the ingredients until the onions are golden brown and the mushrooms appear to have released their moisture (about five to six minutes). Then sprinkle the flour over the ingredients and cook for another two minutes, stirring occasionally to coat the ingredients with the flour.
Wet Ingredients. Use a wooden spoon to stir in the beef broth, Worcestershire sauce, Dijon mustard, paprika, salt, and black pepper. Cook for two minutes stirring and gently scraping the brown bits (deglazing) from the bottom of the Dutch oven (this will release essential flavors).
Simmer. Carefully return the seared beef, from the first step, to the Dutch oven, stirring it well so that it is completely covered with the liquid. Bring the ingredients to a simmer and then cover your Dutch oven and reduce heat to low.
Cook. Continue to cook the covered ingredients on low for 1.5 to 2 hours, or until the beef is tender.
Sour Cream. Remove the Dutch oven from the heat and stir in the sour cream, making adjustments as needed for texture.
Serve. You can serve your stroganoff with cooked egg noodles or as desired.