Grind peppercorns coarsely and season steaks with salt and crushed peppercorns.
Cook steaks in a skillet until browned on both sides. Remove from skillet and let rest.
Cook chopped shallot in reserved fat until softened. Add garlic, thyme, and flour; cook until fragrant. Whisk in cognac, then slowly whisk in broth. Add potatoes and simmer until tender.
Stir in cream and Worcestershire sauce and cook until warmed through.
In another saucepan, cook sliced shallots in oil until golden brown and crispy. Drain on paper towels and season with salt.
Divide soup among bowls, top with cubed steak, and garnish with fried shallots. Enjoy your Steak au Poivre Soup!