Whizz together the prosciutto, the
zest of three and the juice from
11⁄2 lemons, the chopped sage and
plenty of seasoning until blended
to give a thick paste. Put aside and
reserve the rest of the lemons.
Cut each tenderloin lengthways
down the centre, but not all the way
through. Open out the meat,
butterfly style, and flatten slightly.
Make about 10 deep slashes in
each tenderloin, cutting about
three quarters of the way through.
Rub the paste over the meat and
into the slashes.
Brush the tenderloins with oil.
Barbecue the meat, paste side
down, for 6-8 minutes. Turn over
and cook for a further 6-8 minutes
until tender and cooked through.
Transfer the pork to a platter and,
while hot, top it with the slices of
butter. Leave for a minute or two to
melt. Squeeze the reserved lemon
halves over the pork (or use fresh
ones). Scatter with sage sprigs,
then serve cut into thick slices.