וַיָּסִ֨ירוּ הָעֹלָ֜ה לְ֠תִתָּם לְמִפְלַגּ֤וֹת לְבֵית־אָבוֹת֙ לִבְנֵ֣י הָעָ֔ם לְהַקְרִיב֙ לַיהוָ֔ה כַּכָּת֖וּב בְּסֵ֣פֶר מֹשֶׁ֑ה וְכֵ֖ן לַבָּקָֽר׃
And they removed the portions that were to be burnt, that they might give them to the divisions of the fathers’ houses of the children of the people, to present unto the LORD, as it is written in the book of Moses. And so did they with the oxen.
Rabbeinu Bahya
ובשלת ואכלת, “you are to boil it and eat it.” The word ובשלת in this connection means “to barbecue it on a spit over an open fire” as we know already from Exodus 12,8. The word בשל occurs in the sense of “ripening, becoming ready for its destiny,” already in Genesis 40,7 when the butler described his dream with the grapes. Similarly, the meaning of Chronicles II 35,13 ויבשלו את הפסח, does not mean that the people boiled the Passover in water, but that they made it ready for eating.