Heat a little oil in a fry pan on medium to high heat. Season eye fillet with salt and freshly ground black pepper and sear for 45 seconds on all sides, so the middle is still rare. Remove and set aside to rest (and cool) for 10 minutes. Lay a piece of cling film, about an arm’s length, out on the bench and wrap eye fillet up in a nice cylindrical shape, twisting the ends of the cling film to secure. Freeze wrapped eye fillet for at least 3 hours until very firm.
Remove cling film from eye fillet and slice very thinly with a sharp knife (slice as thinly as you can). Note: If it has been frozen overnight, allow it to thaw for 20 minutes on the bench so it is easier to slice.
To make the dressing, combine the lime or lemon juice, soya sauce, sesame oil, mirin or sugar, extra virgin olive oil, shallot and chili.
To assemble, lay slices of beef and radish around plates, slightly overlapping. Place a small pile of watercress, carrot and apple in the middle and spoon over a couple of tablespoons of the dressing over the beef. Serve immediately – the beef will be at the perfect temperature, it should be cold but not frozen.