Is preparing a meal for your parent a הכשר מצוה or an actual מצוה of Kibbud Av Va-eim?
The Tosfos in Yevamos [6a] says that it is a הכשר מצוה while Tosfos in Shabbos [קל"א. ד"ה ושוין] says that it is an actual bona fide mitzva.
Firstly, there is a contradiction in Tosfos and it is hard to say that they argue because the Tosfos in Shabbos makes reference to the Gemara in Yevamos and doesn't explain the "monkey in the room" which is the words "שכן הכשר מצוה" [about cooking for your parent] to fit with their opinion.
Also, the Tosfos in Yevamos seems to be correct. The mitzva is to serve your parents food [Kiddushin 31b]. The preparation seems to be a הכשר. So how can we make sense of the Tosfos in Shabbos??
Discussed here. [Hebrew]
With LS"D!! [Lotsa Siyata Di-shmaya].
