How do you deal with technical interviews that are not in your native language?

I speak English fairly well. But when you are in pressure or want to explain of course I feel that urge to switch to native and explain concepts.

What's your trick ?

When I talk technical I have this urge to switch to English from my native language :-)

Yeah. Thats the problem.
You can ask interviewer if he/she can understands the other language.

When I interview I truly don't give a fuck. I know that does not help a lot but I guess this is my advice: realize at the end of the day- software or "programming" is simply logic. If you can demonstrate solid logic about a problem I don't give a flying fuck how thick your accent may be. Also please note, if the listeners are having a hard time...jump over to a whiteboard! Draw it out! No whiteboard available? Bring paper and pen. Be prepared to show off your Math Logic, seriously! You'll do fine, just be your logical Self. Really at the end of the day I know the team can rest upon Logic. Logic don't change, yo.