Serving as the director of the Department of International Law in the Office of the Legal Adviser of Israel's Ministry of Foreign Affairs, Lenk rejoined the Office of the Legal Adviser following the conclusion of his tenure as Israel's ambassador to Azerbaijan in 2009, and worked from 2010 through 2013 as the Ministry's director of the Department of International Law. He was seconded to work during 2010-2011 as a staff member on the UN Secretary-General's Panel of Inquiry on the Gaza flotilla raid.