Sure you can. McDonald's gave up on the "no microwaves" thing about 20 years ago. I was managing a McDonald's when we got our first microwave. Before that you'd just have to wait for the sandwich was made fresh (the McRib's were grilled and then put in a bain-marie pot filled with barbecue sauce.

What made me laugh was that the employees were not allowed to call it a microwave -- it was known as a "Q-ing" oven. Good times (actually, they were in a lot of ways -- too bad I really couldn't make a real well-paying career out of it).

After McRib season, I'd always end up with a gallon or two of the barbecue sauce.