If I'm at a picnic, how do I ensure this stays at a safe temperature?
Since this is served cold, you should either remove it from the table once 2 hours have passed (putting it back in a fridge/cooler or tossing out), OR find a way for it to be served in a larger container of ice so that it stays at 40 degrees or less. Lots of good safe food practices for picnics and potlucks here!