How to Make It
Heat oil in a large non-stick skillet over medium-high. Add beef, and cook, stirring to crumble, until browned, about 6 minutes. Add onion, turnip, carrot, garlic, rosemary, 3/4 teaspoon of the salt, and 1/2 teaspoon of the pepper; cook, stirring occasionally, about 5 minutes.
Whisk together stock and flour in a bowl, and stir into beef-vegetable mixture. Bring mixture to a boil; reduce heat, and simmer 4 minutes. Stir in peas.
Prepare potatoes according to package directions. Add milk, sour cream, butter, and remaining 1/2 teaspoon salt and pepper; mash until desired consistency.
Divide potatoes among 4 shallow bowls, and top evenly with beef-vegetable mixture. Sprinkle with parsley.