Preheat a grill or skillet over high heat and add a little oil. Sear the steak for about 4-5 minutes on each side for medium-rare, or to your desired doneness. Remove from heat and let it rest.

Making the Persillade

Mix the Persillade

In a small bowl, combine the bone marrow, parsley, minced garlic, lemon zest, salt, and pepper. Mix well and set aside.

Preparing Kohlrabi Écrasé

Cook Kohlrabi

Boil the kohlrabi cubes in salted water until tender, about 10-15 minutes. Drain and return to the pot.

Mash the Kohlrabi

Add butter, salt, and pepper to the cooked kohlrabi. Mash until smooth but with some texture. Set aside.

Making Creamed Onion

Cook the Onions

In a skillet, melt the butter and add the chopped onion. Cook until soft and translucent, about 5-7 minutes.

Add Cream

Pour in the heavy cream, and season with salt and pepper. Simmer until thickened, about 5 minutes.

Preparing Red Wine Jus

Make the Jus

In a saucepan, combine red wine and beef broth. Bring to a boil, then reduce to a simmer and cook until reduced by half. Stir in butter, and season with salt and pepper.

Plating

Serve the Dish

On a plate, place the kohlrabi écrasé, top with the sliced steak, spoon over the creamed onion, and drizzle with red wine jus. Finish with the smoked bone marrow persillade on top.