If you're planning to keep leftovers, store the potatoes separately from the sauce. The potatoes will last for 4 to 5 days in the refrigerator in an airtight container, but they are definitely best served when fresh. And if you're anything like me, there will be no leftovers ;)  If you have leftovers of the sauce, store it in a small jar in the fridge for up to 1 week.