Heat oven to 500. Toss in bowl, turnips, potatoes, 1 tbsp oil, marjoram, 1/2 tsp salt and 1/4 tsp pepper. Spread evenly on lg baking sheet. Roast 15 mins.
Place flour in shallow bowl, take 2 tsp of flour and put in a small bowl, whisk into the small bowl, the chicken broth. set aside. Season chicken w/ remaining salt and pepper. Dredge in flour. Heat 1 tbsp oil in lg skillet over medium heat. Brown chicken on all sides. Remove from heat. Take veggies out of oven and stir.
Place chicken in each corner of baking sheet. Roast 30 mins. or until juices run clear. Place a skillet over medium heat. Add shallots, cook 1 mins, stirring. Whisk reserved broth/flour mix into pan. Bring to a boil. Cook, stirring until reduced by 1/2. Stir in mustard and vinegar. Serve sauce w/ chicken and veggies. Or spoon sauce over chicken right before serving.