Wash the ham hocks in cold water and put them into a large pot with the onions, carrots, bay leaf, cloves, peppercorns and thyme.
Cover with cold water, bring to the boil and simmer for 3 hours.
Remove the hocks from the cooking liquid and leave to cool.
To make the sauce:
Simmer the shallots, English mustard and white wine together until completely reduced.