Heat a 12-inch cast-iron skillet over medium-high heat and get it as hot as the sun. Open any kitchen windows and turn on your hood fan (trust me).
Brush all sides of each steak with olive oil and season well with salt and pepper. Remember, you can’t season the inside of the steak, so go extra generous on the outside.
Place your steaks in the skillet and immediately set a timer. Every minute on the minute, flip the steaks. At the 7-minute mark, add the butter, garlic, thyme and rosemary to the skillet. Continue cooking, constantly basting the steaks with garlicky herb butter and flipping every minute, until a digital thermometer inserted in the thickest part of the steaks reaches 130°F (perfect for medium-rare, as the internal temperature of the steaks will continue increasing as they rest). Transfer to a cutting board and let rest at least 7 minutes.
While your steak rests, finish frying your fries and make your whisky peppercorn sauce. Heat the oil until it reaches 375°F on a deep-frying thermometer. Working in batches, cook the fries again for 2 to 4 minutes, until golden brown and crispy. Drain on the wire rack, and generously season with salt. Let the oil return to 375°F before each batch.
Heat the peppercorns in a medium skillet over medium-high heat and toast for 2 minutes. Add 2 tbsp of the butter, shallots, garlic and a pinch of salt, and cook, stirring often, until the shallots are softened, 3 to 4 minutes. Remove the skillet from the heat and add the whisky. Return the skillet to the heat and allow flame to burn off the alcohol, about 1 minute (you can use your trusty barbecue lighter to light a flame here – just be very careful, please).
Add the cream, stock, any juices that have come out of the resting steaks and lemon zest and bring to a boil. Let the sauce cook until thickened, 2 minutes. Remove from the heat, stir in the remaining 2 tbsp of butter and season to taste with salt.
Slice the steaks against the grain into thin slices. Divide among four plates and spoon some of the sauce over. Serve with a pile of fries alongside.