For the beef, season the beef fillet with salt and freshly ground black pepper. Heat a frying pan until smoking, add the olive oil and sear the beef for 2-3 minutes on all sides, until golden-brown.
Remove the beef from the pan and cover in cling film and roll into a barrel shape, twisting tightly at both ends to seal. Refrigerate for 1 hour, or until firm.
For the pickles, put the sugar, vinegar, salt and 400ml/14fl oz water into a non-reactive pan and bring to the boil. Pour half the pickling liquor into a separate pan. Add the beetroot to one pan and the shallot to the other, then remove from the heat and set aside to cool. Drain well.
For the salsa verde, put all the ingredients in a pestle and mortar and pound until you have a thick paste.
Heat a griddle pan until hot. Rub the sliced sourdough with the garlic and drizzle with some of the olive oil. Toast the bread in the pan for 1-2 minutes on each side, or until charred.
To serve, slice the beef and lay it on a large serving plate in a fan shape. Dot salsa verde around the plate and garnish with the bull's blood and watercress leaves and red onion. Drizzle with the extra virgin olive oil and serve with the pickles and bread.