Prepare the vegetables. Peel and slice the potatoes into thin, uniform slices (about ⅛-inch thick). Chop the onion, mince the garlic, and slice the mushrooms if using.
1 medium onion, 2-3 cloves garlic, 2 pounds russet potatoes, 8 ounces fresh mushrooms
Brown the ground beef in a large skillet over medium heat until no pink remains, breaking it up with a wooden spoon as it cooks (about 5-7 minutes). Drain excess fat if necessary.
1 pound lean ground beef
Add the chopped onion to the skillet with the ground beef and cook for 2-3 minutes until softened. Then add the garlic and sliced mushrooms, cooking for another 2-3 minutes until mushrooms begin to soften.
1 medium onion, 1 teaspoon garlic powder, 8 ounces fresh mushrooms
Add the sliced potatoes to the skillet. Pour in the beef broth and add Worcestershire sauce, garlic powder, thyme, paprika, salt, and pepper. Stir gently to combine.
2 pounds russet potatoes, 2½ cups beef broth, 1 tablespoon Worcestershire sauce
Bring the mixture to a simmer, then reduce heat to medium-low. Cover the skillet and let simmer for about 15-20 minutes, or until the potatoes are fork-tender. Stir occasionally to prevent sticking.
2 tablespoons olive oil or butter, 1 teaspoon dried thyme, ½ teaspoon paprika, ½ teaspoon salt, ¼ teaspoon black pepper
Once potatoes are tender, reduce heat to low. In a small bowl, combine a few tablespoons of the hot liquid from the skillet with the sour cream and mix well (this prevents curdling).
¾ cup sour cream
Gently stir the tempered sour cream mixture back into the skillet until completely incorporated into a creamy sauce.
Taste and adjust seasonings if needed. Garnish with fresh chopped parsley before serving.
2 tablespoons fresh parsley