Heat oven to 190C/fan 170C/gas 5. Peel
the potatoes and cut in half; if very large, cut
into quarters, or leave whole if they are small.
Tip into a saucepan, cover with cold water,
then bring to the boil. Set the timer and boil
for exactly 2 mins. Drain the potatoes well,
then toss in the colander to fluff up their
surfaces, sprinkling over the flour as you go.
Place a large, sturdy roasting tray over a fairly
high heat, then tip in the fat and oil. When
sizzling, lower in the potatoes carefully, then
gently brown in the hot fat for about 5 mins
so all the sides are covered with oil.
Roast undisturbed for 20 mins, then remove
from the oven and gently turn them over with
a fish slice. Place the tray on the hob to heat
the oil, then return to the oven and cook for
another 20 mins. Turn again, putting the tray
back on the hob to heat the oil. Give them a
final 20 mins in the oven, by which time you
should have perfect roast potatoes.