Bill asked just what it is that Zuhdi Jasser would ask Islamists in public in order to make them reveal their true positions. Here's a recent analysis Jasser did of a video purporting to turn Muslims against terrorism. It's rather long and detailed, but gives an idea of his approach. Essentially, he argues that meaningless verbiage about 'extremism' is just that - meaningless.
For a short version of the key questions to ask, here's a 'quiz' developed by Dr. Tawfik Hamid, an Egyptian-American who once belonged to a radical group and is now an outspoken opponent of Islamism. Dubbed the Radical Islam Support Test, it's presented in his excellent book, Inside Jihad (pp. 114-15):
Apostates: Do you support killing them? Should leaving the faith of Islam be punishable by death?
Beating women: Is beating women ever acceptable and if not, do you reject those decrees of Islamic law that sanction the beating of women? Do you also accept stoning women to death for committing adultery?
Calling Jews 'pigs and monkeys': Do you believe that Jews are in any way sub-human and if not, do you reject Quranic interpretations that claim they are?
Declaring Holy War: Do you support declaring war against non-Muslims to subjugate them to Islam? Do you believe that it is fair and reasonable to offer non-Muslims three options: Conversion, Paying the Jizya (discriminatory poll tax), or Death?
Enslavement: Do you support the enslavement of female war prisoners and having sex with them as concubines? If not, do you reject those interpreations in Islamic Law ... which justify such actions?
Fighting Jews: Do you support perpetual war against Jews to exterminate them, and if not, should those Muslims who incite such war be punished?
Gays being killed: Do you believe it is acceptable to kill Gays, and if not, do you reject those edicts in Sharia Law which claim it is?
Hamid concludes: "If a Muslim or Islamic organization fails this quiz, they can safely be regarded as Salafists (Islamic fundamentalists) regardless of any title they use to describe themselves."