Yes, you can freeze arancini either just after crumbing it (before frying) or after it has been fried. To freeze crumbed (unfried) arancini, arrange the crumbed balls on a baking sheet (which has been lined with baking paper to prevent sticking) and place them into the freezer until the balls are solid. Transfer the frozen balls into a suitable container and freeze for up to 3 months. Fry from frozen, but don't allow the oil to get too hot or the breadcrumbs may over-brown before the inside has had time to defrost. To freeze fried arancini, arrange them on a baking sheet in the same way as the unfried arancini. Once solid, transfer to a suitable container and freeze for up to one month. To reheat, arrange the balls on a baking tray and bake in a hot oven (200C/400F) for 15 to 20 minutes until the outside is crispy and the inside is completely warmed through. The tomato sauce can be frozen in a rigid plastic container and then defrosted and warmed in a saucepan over a low heat.