Heat oven to 160C/140C fan/gas 3.
Sit the pork on a sheet of foil in a roasting
tin. Mix the butter, sugar and mustard
with 2 tsp salt, rub all over the top and
ends of the joint (or joints), then scrunch
up the foil to seal tightly in a parcel.
Mix the onions and apples in a large,
shallow roasting tin. Scatter the peppers
over the top and poke in some bay
leaves. Mix the vinegar, oil, mustard and
sugar with 100ml water and drizzle over
everything. Roast the pork for 3½ hrs
while you cook the peppers on the shelf
below for the first 2 hrs. When you
remove the apples and peppers after
2 hrs, set aside and put the Salt-baked
potatoes (see 'Goes well with', right) into the oven
underneath the pork instead.
After 3 hrs, unwrap the foil from the
pork. Scrape any mustard mixture stuck
to the foil back onto the pork, sit it and
any juices back in the tin and increase
oven to 200C/180C fan/gas 6. Roast for
30-45 mins more until the skin is brown
and crisping. Remove the pork from the
oven, cover and rest for 20 mins while
you put the peppers back on the top
shelf for 20 mins to finish. Serve the pork
thickly sliced alongside the apples and
peppers, with any tin juices poured over.