This recipe makes a lot of crepinettes, but caul fat comes in large sheets -- and, once made, these freeze well. You can cut the recipe in half, too. Obviously you don't need wild boar here: Any decent quality domestic pork will work just fine. You can also do this with lamb, venison or turkey. Really the sky's the limit.
Cut the boar or pork shoulder into cubes large enough to fit into your meat grinder. Mix the salt and all the herbs and spices in with the meat, then grind through the coarse plate on your grinder. Mix in the chestnuts (if using) by hand. If you are using pre-ground meat, mix in everything at once by hand.
Put the caul fat into a bowl of lukewarm water. Gently unfold it and lay it out flat on a large work surface, like a pasta board, large cutting board or a counter or tabletop.
Form the meat into small patties. Size and shape is your option: I like patties the size of breakfast sausage patties, but you could go larger if you like. Many crepinettes are torpedo-shaped, so you could go that route, too. Lay each patty on the caul fat and, using a sharp knife, cut a square of caul fat around the patty a little larger than the meat: You need it to wrap completely around the patty. It is better to have too much fat than too little. It renders away, for the most part. Set each completed crepinette on a cookie sheet, seam side down. Refrigerate for 1 hour before you cook them; this helps the crepinettes hold their shape.
To cook, set the crepinettes seam side down in a large saute pan and turn the heat to medium-high. When they start to sizzle, turn the heat down to medium and let them sizzle gently for 10 minutes or so. Do not be tempted to rush this. Crepinettes are best cooked at a leisurely pace. When the seam side is nicely browned, flip and cook for another 6-8 minutes on the other side. When that side has browned, serve them up hot.