Wow, I was able to do everyday this week. Thank you all for your kind words and wishes:
On to the d’var todah ( well before licht today 😉 )
The following is said in the name of R’ Shlomo Zalman Aurbach zt”l:
Why is the door closed during Ha Lachma Ania yet opened during Sfuch Chamoshcha?
R’ Shlomo Zalman explains that one of the dinim of the Korban Pesach was that it needs to be eaten in one place, and it was forbidden to take the meat outside. However, the Hallel (which was said after the eating of the Korban Pesach) was able to be said in a place other than where the Korban Pesach was consumed.
Therefore, up until the point of the consumption of the Afikoman (which is a zecher for the Korban Pesach) the door remains closed (in order to prevent ‘traffic’), however, once the Afikoman has already been eaten and we begin to say Hallel, we open the door as the din preventing ‘traffic’ no longer applies.