Place the trotters, whole heads of garlic, bay leaves, thyme, cider and Calvados, if using, in a pot. Bring up to the boil, and reduce to a simmer. After 2 hours add the tripe. Cook for approximately another 1–1½ hours, until the tripe and trotters are cooked: when you pinch them, your fingers easily go through the flesh. Remove the tripe, trotters, herbs and garlic from the liquor, which you should leave cooking to reduce by half. Pull the flesh off the trotters while still warm and add to the tripe, discarding the bones.
Meanwhile sweat in the duck fat the shallots, carrots, leeks and chopped garlic until softened, but not a pulp. Add the tomatoes, crushing them in your hand as you do so, and let this mixture cook for a further 20 minutes, sweetening the tomatoes (you are not looking to make a tomato dish, just bring the faintest blush). Now add the tripe and trotter flesh to the pot with a few ladles of the liquor, and season to taste. Remember that this will be served cold, so slightly overcompensate. Let this cook gently together for another 30 minutes.
Line a terrine mold or bread tin with cling film. Spoon in the tripe, trotter and vegetables with a slotted spoon, topping up at the end with liquid so they’re just covered. Make sure, by banging the mold on the table, you are not left with any gaps or air holes. Cover with cling film and leave in the fridge overnight to set.
When firm, remove it from the fridge to acclimatize without getting too warm, and slice it as you would a terrine: you should have a beautiful cross-section through a tripey weave. Serve with chicory salad dressed with Dijon mustard, red wine vinegar, extra-virgin olive oil, capers and parsley.