Gently season the Onglet steaks with salt and pepper, then roll in the cocoa powder until all sides are lightly covered.
Take a non-stick frying pan and drizzle a little oil inside and bring to a medium heat.
Add the Onglets to the pan and sear on all sides, allowing to cook for about 7/8 minutes. The steaks will have some colour because of the cocoa powder. For best results cook to medium rare then remove from the heat allow them to rest.
While the steaks are resting, make the salad by finely slicing the fennel and apples. Drain the liquid from the pickled walnuts then cut them into quarters.
Mix the apple, fennel, walnuts and watercress with the ranch dressing and taste for seasoning.
Gently heat the steaks in a hot oven for a few minutes then slice and serve with the salad.