In a large Dutch oven or heavy-bottom pot, heat the olive oil over medium-high heat. Once the oil is shimmering, add the beef cubes in a single layer. Sear the beef for about 5-7 minutes, turning occasionally, until browned on all sides. Once browned, remove the beef from the pot and set it aside on a plate.
Using the same pot, reduce the heat to medium. Add the finely chopped onion and minced garlic. Sauté for about 3-4 minutes, stirring frequently, until the onion is soft and translucent, releasing its aromatic flavors.
Stir in the diced tomatoes along with the dried oregano, ground cinnamon, and a generous pinch of salt and pepper. Cook the mixture for an additional 2-3 minutes, allowing the ingredients to combine and the flavors to deepen.
Return the browned beef to the pot. Pour the beef broth over the mixture and give it a gentle stir. Increase the heat and bring the pot to a simmer. Once bubbling, cover the pot with a lid and reduce the heat to low. Let it cook for approximately 1 hour or until the beef is tender and flavors are well blended.
Once the beef is tender, add the orzo pasta directly into the pot. Stir the contents well to ensure the orzo is evenly distributed. Check and adjust the seasoning if necessary. Cover the pot again and allow it to cook for an additional 10-12 minutes, or until the orzo is al dente and has absorbed some of the broth.
If you find the mixture is too thick for your preference, add a splash more broth or water to loosen it. Stir thoroughly to combine all elements nicely.
Remove the pot from heat and allow the dish to sit for 2-3 minutes. Serve the Beef Orzo Giouvetsi hot in bowls, garnished with a sprinkle of freshly chopped parsley and a scattering of feta cheese on top for extra flavor and a delightful presentation.