Prep Time: 10 Minutes
Cook Time: 35 Minutes
Total Time: 45 Minutes
1. Heat oven to 375°F. Heat oil and butter in a large, cast-iron skillet (or other heavy-bottomed skillet) over medium-high heat. Add carrots and onions and let cook, undisturbed, until the carrots start to brown, about 6 minutes. Remove vegetables from skillet and add steak, searing both sides, about 5 minutes each. Return vegetables to skillet. Place skillet with meat and vegetables into oven and roast about 15 minutes.
2. Remove skillet from oven. Place steak on plate and cover to keep warm. Place skillet, with the vegetables, on stove top and heat over medium-high heat. Add sherry and scrape up browned bits from skillet. Stir in stock and cook, simmering 5 minutes longer. Add cream. Bring to boil and reduce to simmer. Cook about 5 minutes, until slightly thickened. Stir in dill and mustard.
3. To serve, spoon carrots onto platter. Top with steaks and pour mustard cream sauce over all. Slice and serve.