Heat the oven to 180C/160C fan/gas 4. Put the ham in a large roasting tin and scatter over the garlic, ginger slices, spring onion greens and chilli, if using. Pour over the soy sauce and ginger beer. Cover with a couple of layers of foil, sealing it around the edge of the tin to trap in the steam. Roast for 2 hrs, then leave the ham to rest in the tin for 10 mins. (Or, cook in a slow cooker – below.) Remove the foil, strain off the stock into a heatproof jug and leave to cool for at least 30 mins, or until cool enough to handle. Peel off and discard the thick layer of skin to reveal the layer of fat. This can be done up to two days ahead – chill the ham and stock until ready to roast.

To make the glaze, strain the stock into a saucepan and bring to the boil. Reduce the heat to medium-high and simmer for 8 mins until reduced by half. Stir in the gochujang and honey, bring to the boil and cook for another 3 mins, stirring continuously to combine. Remove from the heat and cool slightly.

Heat the oven to 200C/180C fan/gas 6 and score the layer of fat on the ham in a diamond pattern. Put it, fat-side up, in a roasting tin lined with foil then generously brush over half the glaze. Roast for 15 mins, then brush over the remaining glaze. Return to the oven for 10-15 mins more until the ham is sticky and mahogany coloured. Leave to cool for at least 15 mins, or cool completely before carving. The cooled ham will keep chilled for up to five days or frozen for up to three months.