Answer:
What's as small as a mouse but guards a house like a lion?
What relies on columns but isn't a house, and asks for help but can't speak itself?
Take one out and scratch my head, I am now black but once was red.
What is as big as you are and yet does not weight anything?
I am never quite what I appear to be. Straight-forward I seem, but it's only skin deep. For mystery most often lies beneath my simple speech. Sharpen your wits, open your eyes, look beyond my exteriors, read me backwards, forwards, upside down. Think and answer the question...
This food is a tortilla filled with cheese and sometimes chicken before being heated or cooked.