|1/2||cup Dijon mustard|
|1/4||cup creme fraiche|
|8||tablespoons unsalted butter, or more as needed|
|2||large onions, cut into 1/4-inch dice|
|1 1/4||pounds Yukon Gold potatoes, peeled and cut into 1/4-inch cubes|
|Salt and pepper, to taste|
|1 1/2||pounds beef tenderloin, cut into 1-inch cubes|
|2||tablespoons chopped fresh parsley (for garnish)|
2. In a medium skillet over medium-low heat, melt 2 tablespoons of the butter. Add the onions and cook, stirring occasionally, for 10 minutes or until softened and golden.
3. In a second larger skillet, heat 4 tablespoons butter over medium-low heat. Add the potatoes, salt, and pepper. Spread the potatoes into a single layer and lower the heat to low. Cook, stirring occasionally, until potatoes are cooked through, gradually raising the heat to medium-low so the potatoes color a little.
4. When the potatoes and onions are nearly ready, set the oven at its lowest setting (about 200 degrees). Heat another large skillet over high heat. Add the remaining 2 tablespoons butter. Add the meat in batches. Cook, stirring often, until pink inside, and cooked through. Keep the cooked meat warm in the oven until all the meat is ready.
5. On each of 4 plates, arrange some of the potatoes, onions, and beef in separate mounds. Crack an egg, separate the white and reserve it for another use, and place the yolk in half the eggshell on the plate, setting it in the food so it doesn't slip. Serve with the mustard cream sauce. Adapted from Anders Nilsson