[winternewt]

Ironically I always put the lid in for protection so food doesn't explode and stain the oven. Guess that was a bad idea.

[CrimsonRain]

for that, use an external/separate cover purpose built for this purpose

[lucb1e]

I don't think using a lid is a bad idea, like a plate or so, but maybe not the plastic you were trying to avoid in the first place!