Directions :

1. Grind peppercorns on the most coarse setting of a pepper mill (you can also use a mortar and pestle, or wrap peppercorns in cheesecloth and smash with a meat mallet or bottom of a heavy skillet). Season steaks on both sides with a generous pinch of salt and crushed peppercorns, pressing peppercorns into meat.
2. In a medium Dutch oven over medium-high heat, heat 2 tbsp. oil until shimmering. Cook steaks, gently pressing to make sure you don’t lose any peppercorns, until well browned on one side, about 3 minutes. Flip steaks and add butter and thyme sprigs. Continue to cook, spooning butter over steak, until tops are crusty and well browned and an instant-read thermometer inserted into thickest part registers 135°, 2 to 3 minutes more. Transfer steak to a cutting board and let rest until ready to use. Strain fat remaining in skillet and reserve.
3. Wipe out any large chunks of pepper from Dutch oven. Return reserved fat to pan, then cook chopped shallot over medium heat, stirring often, until softened, about 2 minutes. Add garlic and chopped thyme and cook, stirring, until fragrant, about 1 minute. Add flour and whisk until combined. Cook, whisking constantly, until flour darkens slightly, about 2 minutes. Whisk in cognac until smooth, then slowly whisk in broth. Add potatoes and bring to a simmer. Cook until potatoes are tender and soup is thickened, about 15 minutes. Reduce heat to low and stir in cream and Worcestershire. Cook, stirring, until warmed through and combined, about 5 minutes more.
4. Meanwhile, in a small saucepan over medium heat, cook sliced shallots and remaining 1/2 cup oil, stirring occasionally, until oil begins to bubble around shallots, 2 to 3 minutes. Reduce heat to medium-low and continue to cook until shallots are golden brown, 4 to 5 minutes more.
5. Using a slotted spoon, transfer shallots to a paper towel-lined plate; season with a pinch of salt. Let cool slightly.
6. Divide soup among bowls. Cut steak into cubes, then top bowls with steak and fried shallots.