Season the duck legs with a little salt and place skin side down into a shallow ovenproof pan.
Brown well on both sides, and then add the onions, brown slightly and add the garlic, crumble in the stock cube, chipotle paste (optional) and stir well.
Bring to the boil and cover before transferring to a preheated oven for 1 hour.
After the 1-hour mark remove the pan from the oven and check to see if the duck is cooked, not overcooked. Carefully lift the duck legs out of the stock and place them on a plate and cover with cling film and leave to rest for 30 minutes.
Place the pan back onto the stove and bring the stock to a simmer. Check the seasoning and adjust if needed.
Add a little cold water to the cornflour or arrowroot and mix really well to form a paste.
Stir small amounts into the simmering stock and onions and cook until thickened but not too thick or gloopy and then set aside.
Shred the meat from the duck legs, removing the bone and sharp pin bone from the drumstick. Stir the shredded meat into the duck gravy.
Serve the fries in a bowl and top with the duck gravy and dot with baby mozzarella or home-made curds.