Flat Iron Steak

Flat Iron Steak
Recipe courtesy of:
Chef: Andrew Zimmerman
Serving for 4 people
Ingredient List:
4 pieces of 12 ounce flat iron steaks
12 fingerling potatoes, cut in half lengthwise
1 large turnip, peeled and cut into 1 ½ inch disks, ¼ inch thick
2 clusters of miatake mushrooms, cut into 8 slabs, ¾-1 inch thick
8 knob onions, trimmed, to 2 ½ inches long and cut in half lengthwise
2 cups of rendered duck fat
2 cloves of garlic, in the skins
8 sprigs of thyme
1 recipe coffee soil (recipe follows)
1 recipe béarnaise sauce (recipe follows)
First make the coffee soil and set it aside (it will keep for several days).
In a small sauce pan combine the potatoes, half of the thyme, the garlic and duck fat.
Heat the duck fat to a gentle simmer and cook the potatoes until just tender. Drain the potatoes and reserve the duck fat.
At least 1 hour before cooking, season the steaks with salt and pepper.  
Pre heat the grill (gas or better yet…hard wood charcoal).
Make the béarnaise and keep it in a warm place.
Lightly oil the grill and put the steaks on to cook. They will take about 6-8 minutes per side depending on how hot your fire is.  Cook them to 125 degrees Fahrenheit and let them rest on a rack for at least 5 minutes before serving.
While the steaks are cooking heat a large sauté pan.  Add three tbsp. of the reserved duck fat and start arranging all of the vegetables in the pan cut sides down. (This will help encourage even browning.)  Add the other half of the thyme and season them with salt and pepper. Cook the vegetables until they are lightly browned and cooked through.
Arrange the vegetables and steaks on four dinner plates. Scatter some of the coffee soil around the steaks and serve the béarnaise on the side. 
Coffee Soil: 
250 grams of granulated sugar 
250 grams of almond flour 
150 grams of all-purpose flour 
60 grams of cocoa powder 
50 grams of coffee grounds 
200 grams of butter, melted 
20 grams of kosher salt
Preheat oven to 300 degrees Fahrenheit. Combine all ingredients in a bowl and mix well with hands. Spread evenly in a pan and bake for 12-15 minutes. Cool completely before grinding in a food processor.
Bernaise Sauce:
For the reduction: 
2 medium shallots, minced 
¼ cup of dry white wine 
¼ cup of white-wine vinegar 
10 crushed black peppercorns 
4 large sprigs of fresh tarragon 
Salt to taste 
For the sauce: 
10 ounces (2 ½ sticks) of good-quality unsalted butter 
3 large egg yolks 
3 tablespoons of  water 
Salt and freshly ground pepper to taste 
3 tablespoons of finely chopped tarragon
To make the reduction: Combine the shallots, wine, vinegar, peppercorns, and tarragon in a heavy-based saucepan and simmer over medium high until 2 tablespoons of liquid remains. Strain and discard the solids.
To make the sauce: In a heavy-based saucepan, melt the butter. Simmer it rapidly for at least 10 minutes; the water will evaporate and the milk solids will coagulate on the bottom and sides of the pan. Let the melted butter sit for a few minutes so the solids will fall to the bottom. Skim off the foam on top and then either decant the golden liquid, leaving the solids behind, or pour the melted butter through a cheesecloth-lined strainer. 
Put the eggs and water in a heavy-duty metal mixing bowl (you'll have to hold it by one edge with a kitchen towel over a pot of simmering water). Off the heat, whisk the eggs and water for 30 seconds, whipping in lots of air. Cook the sabayon, whisking constantly and scraping the bowl, until thick and voluminous. The whisk will leave tracks that hold for a few seconds. At this point, take it off the heat and whisk rapidly for 30 seconds to cool it slightly. Add the clarified butter a little at a time, whisking constantly. Be sure the butter isn't too hot or it will break the emulsion.
To finish the sauce, whisk in 1tablespoon of the reduction (or more to taste). Season with salt and pepper. Stir in finely chopped tarragon.