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Ingredients
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Flat Iron Steak
Pommes Aligot (Cheesy Mashed Potatoes)
Sauce Au Poivre (Peppercorn Steak Sauce)
Method
Flat Iron Steak
- 1
Bring steak to room temperature
Pat the flat iron steak dry with paper towels. Season both sides evenly with 2 tsp kosher salt and 1 tsp freshly ground black pepper. Let rest at room temperature for 30–45 minutes while you prepare the other components.
- 2
Sear and finish
Heat a large cast-iron skillet over high heat until very hot (about 5 minutes). Add 2 tbs neutral oil and swirl. Place the steak in the pan and sear, without moving, for 3–4 minutes until a deep brown crust forms. Flip and add 2 tbs unsalted butter, 2 tbs fresh thyme sprigs and the 2 smashed garlic cloves to the pan. Tilt the pan and spoon the butter over the steak (baste) for another 3–4 minutes for medium-rare (internal temperature ~130°F/54°C). Adjust time 1–2 minutes for desired doneness.
- 3
Rest and slice
Transfer the steak to a cutting board and tent loosely with foil. Rest 8–10 minutes to allow juices to redistribute. Slice thinly against the grain into 1/4-inch slices just before serving.
Pommes Aligot (Cheesy Mashed Potatoes)
- 4
Cook potatoes
Place the peeled, cubed potatoes and the 2 peeled garlic cloves in a large pot and cover with cold water by 1 inch. Add 1 tbs fine sea salt. Bring to a boil over high heat, then reduce to a simmer and cook until potatoes are very tender, 15–20 minutes. Drain well.
- 5
Warm dairy and aromatics
While potatoes cook, warm 1 cup whole milk with 4 tbs unsalted butter and the cooked garlic cloves in a small saucepan over low heat until the butter melts and milk is hot but not boiling. Remove garlic cloves and mash or discard.
- 6
Mash and incorporate cheeses
Return drained potatoes to the pot over very low heat for 1 minute to dry. Using a potato ricer or food mill, press potatoes into a clean pot or large bowl to ensure a smooth texture. Gradually stir in the warm milk-butter mixture until silky. Add 2 tbs crème fraîche, 3 oz grated Parmesan and 6 oz grated cheddar/tomme. Stir vigorously (or use a wooden spoon) until the cheeses melt and the mixture becomes elastic and slightly stretchy — the classic aligot texture. If needed, gently reheat very low and stir to reach stretchiness.
- 7
Season
Season with 1 tsp finely grated nutmeg, 1 tsp freshly ground white pepper and 1 tsp coarse sea salt. Taste and adjust seasoning. Keep warm until plating; aligot is best served hot so it retains its stretch.
Sauce Au Poivre
- 8
- 9
- 10
Build the sauce
Add 1 cup beef stock and the crushed 2 tbs green peppercorns plus 1 tsp cracked black peppercorns. Bring to a simmer and reduce by about one-third (4–5 minutes). Lower heat and stir in 1 cup heavy cream and 1 tsp Dijon mustard. Simmer gently until the sauce thickens slightly, about 4–6 minutes.
- 11
Finish the sauce
Whisk in 2 tbs cold cubed unsalted butter, one cube at a time, to give the sauce a glossy finish. Taste and season with 1 tsp salt if needed. Keep warm until serving. Spoon over sliced steak.
