In a large pot, heat a couple tablespoons of olive oil over high heat, sear the beef fillet pieces until browned. Turn the pieces to ensure even cooking. Add 4 cups of beef broth or water and bring the liquid to a boil. Reduce the heat to low, cover the pot, and let it simmer for about an hour.
In a separate pan, heat some olive oil and fry the onions until translucent. Add the Swiss chard stems and continue to fry until both the onions and chard caramelise and shrink. If needed, add a bit of the beef stock to the pan to help in caramelising the onions.
While the beef is simmering, soak the Sumac in 1 cup of boiling water in a separate bowl. Once it's soaked and the mixture has cooled down, add the tahini paste and mix well until smooth. Gradually stir in the flour, ensuring no lumps form, to get a slightly thickened, smooth paste.
Once the beef has been simmering for an hour and is tender, add it to the pan with the onions and Swiss chard. Pour in the sumac-tahini paste and mix everything well. Stir in the chickpeas to the mixture. Adjust the consistency by adding water if it’s too thick; the final mixture should be slightly liquidy. Season with salt and pepper to taste.
In a small frying pan, heat the ¼ cup of extra virgin olive oil. Once hot, add the crushed dill seeds, chilli flakes, and minced garlic. Fry for a couple of minutes until aromatic, ensuring the garlic doesn't burn. Pour half the seasoned oil over the main dish and give everything a good stir.
Transfer the Sumaghieh to a shallow serving platter. Garnish the seasoned oil, sumac and fresh parsley. Serve hot with warm pita bread, and most importantly, enjoy. Sahtein!