Heat oven to 140C/120C fan/gas 1.
Bake the potatoes for 2 hrs until soft to
the middle (alongside the pork is fine).
Toss the potatoes with the olive oil,
most of the spring onions, thyme and
plenty of seasoning in a slightly-too-small
roasting tin. Use the back of a fish slice
or similar to squash the potatoes into
a flat-ish compact cake. Chill until ready
to finish, for up to a day.
Heat oven to 220C/200C fan/gas 7
(when the pork comes out). Drizzle the
spuds with a little more oil and roast for
30-40 mins until golden and crisp. Mix the
salad cream and soured cream, drizzle
over, then scatter with remaining spring
onions and more seasoning, and serve.