Heat half the olive oil in a casserole dish or oven-proof saucepan over a low to medium heat, add the sliced onions and cook for 15 minutes, stirring frequently. Then, remove the onions from the pot with a slotted spoon and set to one side.
Add the remaining oil to the pot and heat for 1-2 minutes. Stir-fry the beef, a little at a time, so not to overcrowd the pot.
Once the beef is nicely browned, return the fried onions to the pot along with the garlic, turmeric and cumin. Stir for 2 minutes.