In a pan, add the oil and fry the onions and garlic until translucent and soft. Add the beef and cook until the meat is no longer pink. Add the cumin, cinnamon and peas. Season well and leave aside.
Boil the potatoes in salted water until soft. Remove from the water, peel and add the butter. Mash until there are no lumps and form small round potato balls, Make a big thumbprint in the middle and spoon the meat mixture into it. Cover the meat mixture with the potato and flatten (like a burger patty). Dip in the egg and cover with breadcrumbs. Deep fry until it becomes a deep golden colour, drain excess oil on a kitchen towel and serve warm.