My grandma used to have us screaming from the kitchen when she made this using a whole pig's head. I kid myself I can remember back to my childhood and what it tasted like though in reality, I'm sure I never was brave enough to even try it. She had enough natural gelatine from the head to make her 'jelly meat' set very firmly but I add a few extra leaves to make sure I get a good wobble. Following her lead, I set it in a bowl and scoop it out rather than in a classic terrine which is turned out and carefully sliced but you can do that, if you prefer.
1.5kg unsmoked gammon knuckle
1 celery stalk, sliced
1 carrot, sliced
1 onion, sliced
few parsley stalks
few peppercorns/star anise/cloves/whatever whole spices you like
sprig of rosemary/thyme/bay leaf
4 sheets of leaf gelatine
5 tbsp white wine vinegar
2 tbsp capers
2 bunches of parsley, finely chopped
Place the gammon and the flavourings in a large pan, cover with water, bring to the boil and simmer for 2 - 21/2 hours until the meat is fully cooked through, skimming the surface from time to time to help keep the stock clear.
Strain through a colander into a large bowl. Set the gammon on a board and leave to cool. Line a fine sieve with some muslin and pour through the stock. If it's a little cloudy, rinse out the muslin and pass it through again. Pour 750 ml into a pan (use the remainder of the stock and bit of the gammon for a classic pea soup) and bring to the boil then turn off the heat, stir in the vinegar and leave to cool a little.
Soak the gelatine in cold water for 5 minutes.
Cut the fat away from the gammon then tear or chop the meat into small pieces. Place in a serving bowl with the capers and parsley.
Squeeze the water out of the gelatine and stir into the hot but not boiling stock. Once dissolved, pour over the ham. Mix gently together, leave to cool then cover and chill overnight. Serve with stacks of hot, buttered toast.