Melt 2 tablespoons butter in a 2-quart saucepan.

Add shallots and cook until clear. Break the chocolate into pieces and add to the butter and shallots.

When chocolate is melted, add the demi-glace and stir to combine.

Add the port and rosé, and bring to a simmer.

Add the balsamic crema, stir, and let simmer for about 30 minutes, stirring frequently, until thickened (sauce will continue to thicken as it cools).

Strain into a clean saucepan, add remaining 3 tablespoons butter, stir until melted, and set aside.

Place cocoa powder and crushed peppercorns on a plate and add salt and sugar. Mix well with a fork. Press tops and bottoms of the filets into the mixture, leaving sides uncoated. Let sit at room temperature while you prepare the potato-sunchoke purée.

Bring a large saucepan of water to a boil.

In the meantime, peel the Jerusalem artichokes, and cut them into 1/2-inch dice.

When the water is boiling, add 1tablespoon salt and the diced Jerusalem artichokes. Cook for 15 minutes.

While the sunchokes are cooking, peel and cut the potato into 1-inch pieces. After the sunchokes have cooked for 15 minutes, add the potatoes to the pot and cook for 20 minutes longer.

Drain, then mash with a potato masher, add butter and cream, then whip using a handheld mixer until smooth. Season to taste, then cover and set aside.

Place a skillet (large enough to cook the filets uncrowded in a single batch) over medium-high heat. When hot, add the oil. Sear filets - 4 minutes per side for medium-rare. Cover and let rest for 5 minutes.

While the steaks are resting, reheat the sauce and potato-sunchoke purée over medium-low heat. (Most likely, the sauce will have separated a bit - whisk it vigorously to emulsify.)

Place a heaping 1/2 cup of potato-sunchoke purée on each plate. Slice the steaks and arrange atop the purée. Spoon sauce over, and serve immediately.