Short version: Is it better to switch focus as a postdoc or wait until after tenure?
Details: I'm a PhD student in math (combinatorics) graduating next year. Let's suppose that I'm a strong candidate for research-oriented, tenure-track positions in math, but my long-term research program is interdisciplinary with TCS. If I have a really productive 1-2 years of postdoc in TCS, will I have a shot at being hired in a good CS department in the US?
I'd rather be in a CS department, but many people in my area don't share that enthusiasm (or are located in Europe). I'm worried that I'll end up with papers in both general math journals and STOC/FOCS and still be unhireable. Should I wait until after tenure?
Edit: Here's why I'm asking. I have postdoc offers in both math and CS departments - I want to take the CS one, but all of my publications are in math journals, and the CS postdoc won't make me a stronger candidate for math departments.