The Paschal Lamb

There are those who say that it means raw. There is no other such usage of this word in Scripture.

נא, I believe this means a type of frying in a pot but in its own juice (including the blood) not involving water known as צלי קדר, not roasting directly on the fire, as required by our verse here [so that the blood drips off].

(2) The roots of this mitzvah is -- as was written about its slaughtering (Mitzvah 5) -- is to remember the miracle of the exodus from Egypt. And that which we have been commanded to specifically eat it roasted is because such is the way of the children of kings and ministers, to eat roasted meat - as it is a good and tasty food. And the rest of the people only eat the little meat that they [are able to acquire] boiled, in order to fill their stomachs. And it is certainly fitting for us - that eat the Pesach sacrifice [to remember] that we went out into freedom to be a nation of priests and a holy nation - to behave in a manner of freedom and nobility in its eating. This is in addition to the concept (see Guide for the Perplexed 3:46) that the eating of roasted meat indicates the haste with which they left Egypt and could not delay; there was simply not enough time to cook it in a pot.

אל תאכלו ממנו נא, “do not eat any of it while it is still raw;” according to Ibn Ezra, the reason for this prohibition is that seeing that we had slaughtered an animal that was an abomination for the Egyptians the Israelites would not dare to roast or cook it for a long time in order that the Egyptians would not become aware of what they were doing; the Torah insists that everything they were doing should be performed in such a way that the Egyptians would be completely aware of it, hence the line: ראשו על כרעיו ועל קרבו, “its head with its legs with its entrails.” It must not be boiled in a pot as then it would not be seen by the Egyptians, as the pots had lids.

We were commanded to eat it ‘roasted over the fire, its head with its legs and with its innards’, because as was already explained this sacrifice was commanded to us by the Holy One Blessed Be He to demonstrate His Oneness in the world, and therefore it had to roasted whole, head, legs and innards, representing unity. That is also why we were commanded to eat it roasted, because cooked meat separates into parts in
cooking, whereas meat that is roasted becomes more solid and unified. That is also why G-d commanded not to eat it raw and not fully roasted because only when properly roasted does all the moisture leave
and the meat becomes compact and hard.
Likewise, we were commanded to slaughter the Pesach in the afternoon which is a unique time, neither part of the day that has passed nor part of the night, and because the time period is unique, it is fitting for a sacrifice for the One who is Unique.