Finely dice your onion then pick the leaves from your thyme sprigs and set aside.
Heat a dutch oven over medium heat, once it's hot add 1 Tbsp of vegetable oil and spread it to coat the bottom of the pot. Add the ground beef and leave it to sit undisturbed for 4-5 minutes. When you start to break it up the bottom of the beef should be a deep brown and easily lift from the surface of the pot.Add the diced onions and continue to stir and break up the meat until it is fully cooked. Add the thyme leaves, oregano, cinnamon, nutmeg, a heavy pinch of salt and fresh ground pepper to the pot and cook stirring constantly for one minute until the spices have bloomed and are fragrant.
Add the beef broth to the dutch oven and allow it to come to a simmer.Meanwhile, shred the potato on a box grater, there is no need to peel the potato, and add to the pot. Allow the mixture to gently simmer until the liquid is mostly evaporated and the meat is tender. The simmer should be gentle, if you need to decrease the heat do so, this process will take 30 minutes.
When the filling is finished allow it to cool. This can be done by spreading it out on a pan, and when it is no longer hot transfering the pan to the fridge.