I have a question about pesto sauce?!
Answers:
Yes, pesto is just basil, pine nuts, cheese, oil and sometimes a little cream. As long as it's been kept properly it's good to eat straight from the container. You don't really cook the pesto when it's on pasta, you just dress cooked pasta with it, it doesn't really cook it.
It is terrific that way, particularly warm sandwiches. And a tip... pine nuts are outrageously expensive, i have used roasted sunflower seeds as a substitute and they work just fine, slightly different taste but still wonderful. Also, try experimenting...another good pesto is with cilantro (instead of basil), jalapeno, garlic and roasted smoked almonds... goes great with grilled chicken!
personal experience
absolutely safe... but I don't think it will taste good in a cold sandwich. I would say stick to a warm grilled sandwich like a chicken panini or something. It's an oil based sauce and that does not sound good cold.
Good luck!
Yes, and really good with chicken, or turkey, maybe add some cheese? Yum!