• Heat half the olive oil in a large pan and cook the pancetta for a few mins until golden.
  • Remove with a slotted spoon and set aside.
  • Dust the steak with the flour, then brown in the hot pancetta oil - to stop the pan getting overcrowded, do this in two batches.
  • Return all the steak to the pan along with the pancetta.
  • Add the wine and thyme and bring to the boil.
  • Partially cover with a lid, leaving a gap of about 1cm, and simmer for 2 hrs until the meat is tender, stirring from time to time, and once the sauce has thickened and reduced a little, cover the pan completely.
  • Meanwhile, heat oven to 200C/180C fan/gas 6.
  • Toss the remaining olive oil and the shallots together.
  • Spread out on a baking sheet and roast for 45 mins until soft and golden brown.
  • To make the pastry crust, sift the flour and mustard into a large bowl, then coarsely grate in the frozen butter.
  • Drizzle over 6-8 tbsp cold water and taking care not to over-handle it, lightly bring together to make a firm dough.
  • Wrap and chill for 30 mins.
  • Stir the roasted shallots, jelly and vinegar into the beef and season, then spoon into a 2-litre pie dish.
  • Raise the oven temp to 220C/200C fan/gas 7.
  • Roll out the pastry and lay over the filling - it's a good idea to use a pie funnel to support the pastry and prevent it going soggy in the centre, but it's not essential.
  • Mix the egg yolk with a little salt, then brush over the top of the pastry.
  • Bake for 30 mins or until the pastry is crisp and golden and the filling is hot right the way through.