I don't remember any policy position like that. But where did the impression of extremism come from then? It could be his rhetoric, such as calling Obama an apologist for Islamist terrorists. That's an extreme thing for an elected official to say out loud. It's more typical of political shock-jocks, not those who are supposed to be responsible, judicious, and fair.
Looking at Cruz's rhetoric, it's easy to find violations of the norms. He'll imply that Obama is a totalitarian, or that former senator Chuck Hagel was in the pay of North Korea. He'll advocate carpet bombing in the Mideast, as though carpet bombing didn't mean killing or wounding every living person in the effected area. It's the equivalent of say "Kill them all and let God sort them out."
His associations are scary. His father, Rev. Raphael Cruz, who frequently campaigns with Ted (making it hard for the son to distance himself) says such things as Obama is trying to destroy Christianity in the US. Other extreme associations include supporters of Uganda's death penalty for homosexuals.
Cruz's tactics aren't mainstream. When the GOP in Congress was voting in vain to repeal Obamacare, Cruz encouraged the 'defund Obamacare' strategy, though perhaps it was rhetoric and not meant to be seriously followed as a strategy. Nonetheless, it led to a government shutdown, and Cruz got much of the credit and/or blame.
I'm not sure I can point to other tactics that might be considered extreme, so I guess Cruz's extremism is primarily in his rhetoric and somewhat in his associations. But there's plenty of that. Just Google it.
Extras. Quite the catalog on Ted Cruz at Right Wing Watch. Outlawing abortion without a constitutional amendment? Totally possible. Here are those 8 outrageous quotes. A fake Cruz quote, so don't trust memes.