Heat your oven to 230°C/Fan 210°C/Gas 8. Unwrap your pork and pat it dry. Place in a roasting tin and let it get to room temperature.
Drizzle over 1 tbsp oil. Sprinkle over a generous scattering of salt and a few cracks of black pepper.
Roast the pork for 30 mins till the skin is beginning to crackle.
Halve the garlic bulb. Wrap it tightly in a square of foil.
Remove the pork from the oven and baste the skin well. Lower the oven temperature to 160°C/Fan 140°C/Gas 3. Drop the whole, unpeeled shallots and the foil-wrapped garlic bulb into the dish next to the pork. Return the pork to the oven and gently roast for 1 hr.
After an hour, lift the pork from the tin and cover with foil. Leave to rest for at least 30 mins.
Allow the shallots and garlic to cool a little. Peel the shallots, keeping them as whole as possible. Place back in the roasting tin and pop in the oven set to a low temperature to warm through.
Squeeze the softened roasted garlic cloves from their papery skins into a small bowl. Strip the leaves from the thyme and mix with the garlic and Dijon mustard. Pour in any juices from the pork plate.
Slice the pork thinly. Serve with the roast shallots and the roasted garlic mustard.