The Bible tells us that Jesus and his Apostles ate fermentation-free bread during his Last Supper, and that they dipped the bread into something that was in a bowl (or bowls). Ancient Bibles call this a sop.
What was sop? A gravy?
No, it was likely a mixture of olive oil, herbs, and salt. This has been a favorite dipping sauce for bread for countless generations (try it sometime, if you are unfamiliar with it).
It probably wasn’t gravy or meat sauce, because they sacrificed and ate the lamb on the following night (see the commentary, The Passover and the Lord’s Evening Meal), and in ancient times people didn’t normally eat meat with every meal. Instead, the Bible reports that the Passover celebration involved the eating of bitter herbs and bread, and they likely used salt and olive oil to add flavor and to soften the bread.