1. Rinse the rice under cold running water until the water runs clear. Drain well.
2. Pat the beef dry and season generously with salt and pepper. Heat the oil in a large Dutch oven or heavy-bottomed pot over high heat. Working in batches, brown the beef on all sides until deeply golden, about 4 minutes per batch. Transfer to a plate.
3. Return all the beef to the pot and reduce the heat to medium. Add the onions and carrots and cook, stirring occasionally, until the onions are soft and the carrots are tender, about 12 minutes.
4. Add the cumin, turmeric, barberries, peeled garlic cloves, and a generous pinch each of salt and pepper. Stir well to coat everything in the spices.
5. Nestle the whole head of garlic and tomato into the center of the pot. Spread the rice evenly over the meat and vegetables without stirring. Carefully pour in enough hot water to cover the rice by about 1 inch.
6. Bring to a gentle simmer over medium-high heat. Cover tightly, reduce the heat to low, and cook undisturbed for about 40 minutes, until the rice is tender and the liquid has been absorbed.
7. Remove from the heat and let rest, covered, for 15 minutes. Invert the plov onto a large serving platter, gently fluff the rice, and serve warm.
