Remove the steaks from their package and pat dry. Season liberally with kosher salt on all sides. We like to tie these with butcher’s twine around their circumference to keep a nice tidy shape. There are two ways to cook these steaks low and slow for reverse seasoning. We like to vacuum seal the steaks in a food safe bag and cook in a sous vide bath at 120 degrees F for 90 minutes. Alternatively, you can set the steak on a cooling rack set inside a sheet pan and cook them at 200 degrees F for about 30 minutes or until they reach 115 to 120 degrees F. Rest the steaks for 5 to 10 minutes while you toast the baguette and make the horseradish sauce.
Heat a large cast iron skillet or griddle over medium-high heat. Coat the baguette halves with mayo and griddle for 2 minutes or until browned and crispy. In a medium bowl, whisk together the remaining mayo, horseradish, lemon juice, Worcestershire with a pinch of salt and pepper. Taste and adjust seasoning.
Crank the heat to high and let the skillet get very hot. Brush the steaks with a little peanut or canola oil and sear them on each side for 1 to 2 minutes. Rest again for 5 minutes before slicing.
Build the sandwiches by slathering the baguette with the horseradish sauce, adding micro greens and adding the sliced steak. Season with more salt and crush these delicious sandwiches, immediately.