Start by making the dough.
Combine dry ingredients in a
bowl, then add water little by
little and bring dough together
using your hands; you should
have a sticky ball. Turn out onto
a floured surface and knead
5 minutes, until smooth and
bouncy, then place in an oiled
bowl. Cover with a kitchen towel
and leave in a warm place to
double in size for 1 to 1½ hours.
Meanwhile, put vinegar for
pickled cucumber into a small
saucepan with 3 Tbsp water.
Bring to a simmer, then pour
into a bowl, add cucumber, and
leave to cool.
Turn dough onto a floured
surface, knead for 1 minute to
knock out air, then divide into
10 equal pieces. Take one piece,
flatten into a ½-inch-thick disc,
then brush one half with a little
oil. Fold bun into a half-moon
and place on a small square of
parchment
paper on
a tray. Repeat with
remaining dough, then
loosely cover tray with a
kitchen towel and leave to
rise for 30 minutes more.
For filling, in a small bowl,
whisk soy sauce, peanut butter,
vinegar, garlic and sesame oil.
Heat canola oil in a frying pan on
high, then fry mushrooms 6 minutes,
until soft and browning at
the edges. Stir in sauce to coat,
then turn heat to medium and
cook, stirring regularly, 5 minutes,
until sauce reduces and darkens.
To cook the bao, set a
steamer over a pan of simmering
water. Put the bao, still on
their parchment-paper mats,
into the steamer in batches,
making sure they don’t touch.
Cover and steam 8 minutes.
Once done, fill each bao
with a generous tablespoon
of mushrooms, 3 or 4 slices
of cucumber and, for a little
crunch, some peanuts.