So tonight I made a batch of roux in the oven, to be used for gumbo tomorrow. I'll be refrigerating it overnight.

My questions are these:

Is it true that, when combining roux with other products, one should be hot and one should be cold/room temp?

If I choose to reheat the roux, what's the best way to do that? Microwave? I am worried that, if I do it in a pan, I might burn it while reheating it.

Any insight on this would be appreciated. Enjoy the SB!