when I reheat meat in the microwave, I wrap it in a damp paper towel. Seems to steam it a bit, and help keep it moist. So far does not seem to make it rubbery, that I can tell.
Great idea! I've been using the microwave on 60% power with the burger in the bun wrapped in a paper towel. Worked OK, but I will try this steam method next time for sure.