To make the mash, boil the celeriac in
salted water for 10 mins until soft. Drain,
put back in the pan and steam-dry for
a few mins. Mash with the butter and
seasoning, then stir in most of the parsley.
Keep warm while you cook the fish.
Heat half the oil in a frying pan. Dust
the fish in flour, season on both sides,
and fry for about 4 mins on each side.
Remove to a plate. Add the remaining
oil to the pan and cook the garlic and
chilli for 2 mins until golden. Add the
vinegar, sugar and a little salt, then
bubble for 1-2 mins. Return the fish to
the pan to warm through.
Serve the fish on the mash, with the
pan sauce poured over. Sprinkle with the
remaining parsley and serve with lemon.