Heat the oil in a heavy-based saucepan over a medium–high heat and gently fry the shallot with a generous pinch of salt for 5 minutes, or until just translucent. Add the garlic and fry for a further minute.
Add the orzo to the pan, stirring until all the pasta is coated.
Add a quarter of the stock and turn down the heat to medium–low. Continue adding the stock a quarter at a time, stirring regularly until the pasta has absorbed all the liquid and is tender but still has a little firmness at the centre. You may need to add a splash more water, or you might not need to use all the stock.
Stir in the oregano, butter, lemon zest and juice, to taste. Season with salt and pepper and serve immediately.
