To make the herby salt, put all the
ingredients in a small food processor
(or use a pestle and mortar) and grind
to a fine salt.
Tip the potatoes into a large roasting
tin and toss with the oil, polenta, 2 tbsp
of the herby salt and some black
pepper. Any leftover salt will keep
for up to 5 days in a small sealed
Bake underneath a joint of meat, if cooking, at
200C/180C fan/gas 6 for 30 mins.
When the meat comes out, turn
up the heat to 220C/200C fan/gas 7
and cook on the top shelf for another
45 mins, shaking the tin halfway through
the cooking time.