Choose a nice and fat pork belly and make sure to trim the skin off.
Sprinkle it evenly with salt & pepper, wrap it in cling film and let it sit for a night in the fridge. The next morning put the pork belly under vacuum and cook it for 12 hours at 85°C. The belly should be very tender and the meat should be pulling off almost by itself. Keeping it in the vacuum bag, lay the piece on an even surface and press it with some weight, not more than 4 kg, however.
Allow it to completely cool down in the fridge. To note the process is almost a day long. - Open the bag and slice some neat pieces of about 150gr.
For the Pork Jus:
Allow the bones to bleed in cold running water for 24 hours. Dry the bones thoroughly and lay in a sheet pan.
Roast it in the oven for 30 min at 450f, or until golden brown. Add it to a large pot with the roughly chopped vegetables, the thyme and the bay leaf.
Cover the whole with cold water. Simmer for two hours than gently strain in a muslin.
For the Tarragon Mustard:
Take a mixer bowl, add the egg yolks, the mustard, the tarragon and the salt and pulse it a few times.
On a low speed, start emulsifying with the oil just like you would do a mayonnaise, by adding a few drops of water every now and then, or when you feel the emulsion is going to split.
Press through a fine strainer and keep it cold.
For the Garnish:
Warm all vegetables in the jus and season it with salt and a little pepper. Keep the herbs and flowers for decorations.
Finalizing the Dish:
In a hot pan, sear four portions of pork belly, the fat layer down, with a slight amount of vegetable oil until it is golden brown and crispy. Do not rush and do not hesitate to lower the heat, this will allow the first layers of fat to render thoroughly and will help you to get a nice and caramelized effect.
Put the seared pork bellies in the oven for 5 minutes at 425f to ensure they are completely warmed. Then lay each portion in the middle of a large bowl and surround with the vegetable garnish and the warm broth.
Just before serving, season the pork bellies with the tarragon mustard and the broth as well, sprinkle the herbs and flowers on top and around the meat.