Mint is not a bitter herb.
The LORD said to Moses and Aaron in the land of Egypt, "This month shall be for you the beginning of months; it shall be the first month of the year for you. Tell all the congregation of Israel that on the tenth day of this month they shall take every man a lamb according to their fathers' houses, a lamb for a household; and if the household is too small for a lamb, then a man and his neighbour next to his house shall take according to the number of persons; according to what each can eat you shall make your count for the lamb. Your lamb shall be without blemish, a male a year old; you shall take it from the sheep or from the goats; and you shall keep it until the fourteenth day of this month, when the whole assembly of the congregation of Israel shall kill their lambs in the evening. Then they shall take some of the blood, and put it on the two doorposts and the lintel of the houses in which they eat them.
They shall eat the flesh that night,
roasted;
with unleavened bread and bitter herbs they shall eat it. Do not eat any of it raw or boiled with water, but roasted, its head with its legs and its inner parts. And you shall let none of it remain until the morning, anything that remains until the morning you shall burn.
In this manner you shall eat it: your loins girded, your sandals on your feet, and your staff in your hand; and you shall eat it in haste. It is the LORD's passover. For I will pass through the land of Egypt that night, and I will smite all the first-born in the land of Egypt, both man and beast; and on all the gods of Egypt I will execute judgements: I am the LORD. The blood shall be a sign for you, upon the houses where you are; and when I see the blood, I will pass over you, and no plague shall fall upon you to destroy you, when I smite the land of Egypt.
"This day shall be for you a memorial day, and you shall keep it as a feast to the LORD; throughout your generations you shall observe it as an ordinance for ever. Seven days you shall eat unleavened bread; on the first day you shall put away leaven out of your houses, for if any one eats what is leavened, from the first day until the seventh day, that person shall be cut off from Israel. On the first day you shall hold a holy assembly, and on the seventh day a holy assembly; no work shall be done on those days; but what every one must eat, that only may be prepared by you.
And you shall observe the feast of unleavened bread, for on this very day I brought your hosts out of the land of Egypt: therefore you shall observe this day, throughout your generations, as an ordinance for ever. In the first month, on the fourteenth day of the month at evening, you shall eat unleavened bread, and so until the twenty-first day of the month at evening. For seven days no leaven shall be found in your houses; for if any one eats what is leavened, that person shall be cut off from the congregation of Israel, whether he is a sojourner or a native of the land. You shall eat nothing leavened; in all your dwellings you shall eat unleavened bread."
Then Moses called all the elders of Israel, and said to them, "Select lambs for yourselves according to your families, and kill the passover lamb. Take a bunch of hyssop and dip it in the blood which is in the basin, and touch the lintel and the two doorposts with the blood which is in the basin; and none of you shall go out of the door of his house until the morning. For the LORD will pass through to slay the Egyptians; and when he sees the blood on the lintel and on the two doorposts, the LORD will pass over the door, and will not allow the destroyer to enter your houses to slay you. You shall observe this rite as an ordinance for you and for your sons for ever. And when you come to the land which the LORD will give you, as he has promised, you shall keep this service. And when your children say to you, 'What do you mean by this service?' you shall say, 'It is the sacrifice of the LORD's passover, for he passed over the houses of the people of Israel in Egypt, when he slew the Egyptians but spared our houses.'" And the people bowed their heads and worshipped. Then the people of Israel went and did so; as the LORD had commanded Moses and Aaron, so they did. (Exodus 12:1-28)