Cut the veal escalopes into pieces about 5 cm (2 inches) across. Season on both sides with salt and pepper.
Heat the oil in a flameproof casserole and quickly fry the veal pieces in two batches for 5 minutes, until lightly browned on both sides, lifting out with a slotted spoon on to a plate. Add the onion to the casserole and fry gently for 5 minutes until softened. Stir in the garlic and fry for 1 minute.
Add the tomatoes to the casserole with the stock, passata, tomato paste and oregano. Bring to the boil and stir in the orzo. Reduce the heat and cook, stirring frequently, for 6–8 minutes or until the pasta has softened.
Return the veal to the casserole and season to taste with salt and pepper. Cook for 2 minutes. Scatter the feta over the meat before serving.