Preheat oven to 400 degrees Fahrenheit. Heat a cast-iron pan and drizzle with oil.

While the pan heats, pat steak dry and generously season with salt and pepper.

When the pan is completely heated, place the meat inside and sear for one minute and 50 seconds on each side. Add garlic, thyme, and rosemary to the pan while the meat sears.

Add stock and transfer pan to the oven. Cook five to 10 minutes (for a medium-rare center).

Transfer meat to a plate and let rest 10 minutes.

While the meat rests, heat oil in a large sauté pan over medium-high heat. Add onions and sauté until translucent.

Add garlic and wine and cook for three to four minutes.

Add brown sugar, ketchup, and vinegar. Cook until mixture attains a jam-like consistency.

Cut ends off potatoes, stand them on end, and peel from top to bottom with a sharp knife to shape each potato into a uniform cylinder.

Cut in half crosswise so that cylinders are about two inches long.

Place potato cylinders in a bowl of cold water for about five minutes to remove starch from the outsides. Pat dry with paper towels.

Preheat oven to 425 degrees Fahrenheit.

In a cast-iron pan, heat oil over high heat until it shimmers slightly.

Stand prepared potatoes on end in the hot oil. Season with salt and pepper.

Reduce heat to medium-high and pan-fry until well browned, five to six minutes per side. As potatoes cook, carefully remove oil from the pan with a paper towel.

Add thyme and duck or chicken fat and spoon over potatoes. Season with salt and pepper again.

Add broth and transfer pan to the oven. Cook until potatoes are tender and creamy inside, about 30 minutes. If potatoes aren’t soft enough, add a little more broth and cook 10 more minutes. Let cool for a few minutes before serving.