How to Make It
Sprinkle beef with pepper and 1 teaspoon salt. Heat oil in a Dutch oven over medium-high. Add beef to Dutch oven; cook, stirring occasionally, until brown on all sides, about 6 minutes. Transfer to a plate.
Add carrots and onions to Dutch oven; cook, stirring often, until carrots and onions start to soften, 4 to 6 minutes. Add garlic; cook, stirring occasionally, 1 minute. Add red wine; cook until liquid has almost evaporated, 10 to 12 minutes, stirring and scraping to loosen browned bits from bottom of Dutch oven.
Whisk together flour and 1/2 cup broth in a small bowl; add to Dutch oven. Stir in beef and remaining 1/2 teaspoon salt and 3 1/2 cups stock; bring to a boil. Reduce heat to medium-low; cover and simmer 45 minutes. Add potatoes; cover and cook until potatoes are tender, about 20 minutes. Stir in mustard and vinegar. Sprinkle each serving with about 1 tablespoon parsley.