How was the Passover lamb required to be cooked and eaten?

The Passover lamb was to be eaten that same night, roasted with fire. Scripture forbids eating it raw or boiled in water; it had to be roasted with fire and not prepared any other way. The fire signified judgment, prefiguring Christ enduring judgment on the cross.

Les explains that after the lamb was kept up for three days and examined for any blemish, sign of poor health, or anything wrong, if it was whole they could kill it for the Passover sacrifice. Then they were to take its blood and strike it on the two side posts and on the upper doorpost of the houses wherein they would eat it. Verse 8 says they were to eat the flesh in that night, roasted with fire. The next verse says they were not to eat it raw, nor sodden at all, or boiled in water, but it was to be roasted with fire. Les sees the fire as indicative of judgment: just as sure as Christ went through the fires of judgment as He hung on the cross to bring about salvation, this Passover lamb also was roasted with fire. It was not to be fixed any other way but this, which indicated a judgment. This pictures Christ, who was without spot, without blemish, and blameless.

Exodus 12:8

And they shall eat the flesh in that night, roast with fire, and unleavened bread; and with bitter herbs they shall eat it.

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How were the Israelites supposed to cook and eat the Passover lamb?

The Passover lamb was to be eaten that night roasted with fire. It was not to be eaten raw or boiled in water, but roasted with fire, a method signifying judgment. They were to consume its flesh in the night, wholly roasted, not raw nor sodden with water, for the fire indicated the judgment Christ would endure.