For the pork rillettes:
Diamond score the skin side of the pork belly. In a small food processor, blend the apple marigold, garlic, fennel seeds and salt with enough oil to make a paste. Spread the paste over the flesh side of the pork belly and wrap tightly in clingfilm. Refrigerate for 24 hours. Place the onion wedges in a roasting tin, unwrap the pork belly and place skin side up on the onions. Pour the cider around the meat. Cover first with silicone paper and then with foil. Cook for 1½ hours at 150℃ and then uncover. Cook uncovered for a further 1½ hours or until the meat is completely tender. Allow the meat to cool slightly and then carefully remove the skin. Increase the oven temperature to 250℃ and cook the skin on a flat tray until nicely crackled. Transfer to a cooling wire. While the pork is still hot remove the bones, sinew and any excess fat. Shred the meat with a pair of forks and transfer to a bowl. Strain the cooking liquid from the roasting tin into a clean pan and skim off (but reserve) the majority of the fat. Reduce to a light syrup.
Peel and finely dice the banana shallot and then cover with boiling water. Allow to sit for 5 minutes and then drain. Mix the blanched shallot, cornichon and reduced cooking liquid into the meat, season to taste and add a little more fat if the mix is dry. Press the meat into a plastic box, cover directly with clingfilm and chill. Allow to come to room temperature before serving.
For the salsa:
Peel the apples and cut into 1cm dice. Melt the butter in a non stick frying pan and, when it is foaming, add ⅔ of the apple. Sprinkle over the sugar and cook until well caramelised. Deglaze with the cider vinegar and remove from the heat. Purée half of the caramelised apple, adding a little apple juice or cider to thin if required, then mix the raw apple, caramelised apple and purée together. Stir in the olive oil, spring onions and apple marigold. Season to taste.
To serve:
Place quenelles of the room temperature rillette mix in the centre of the plates, dot the salsa around and add small apple marigold leaves. Place two or three cornichon slices on the rillette. Chop some crackling to a crumb and sprinkle over the salsa.