Put the pancetta in a large frying pan
and cook until crisp, then lift out with a
slotted spoon and drain on kitchen paper.
Heat the oil in the pan. Sear the liver
steaks for 1-2 mins each side – so they’re
just still pink in the middle – using half
the butter towards the end to baste the
meat. Remove the liver to a plate using
the slotted spoon and leave to rest,
covered with foil, for 10-15 mins.
Add the chopped sage, thyme leaves,
shallots, mushrooms and lemon zest to
the pan. Fry on the highest heat for a few
mins, then add the lemon juice and some
seasoning. Cook for 3-5 mins until slightly
saucy and the mushrooms are soft.
Heat the remaining butter in your
smallest saucepan until just foaming.
Add the remaining whole sage leaves and
fry for a few mins until crisp. Drain on
kitchen paper with the pancetta. Sit the
liver on toast, spoon over the mushroom
mixture and scatter over the pancetta
and crisp sage. Serve immediately.