Answer:
It cannot be seen, it weighs nothing, but when put into a barrel, it makes it lighter.
I am a precious little thing, dancing and eating all the time. Watch me from a distance, so you can feel my warm and gentle love. But don't come to close or my next meal you could be!
I have four legs but no tail. Usually I am heard only at night.
In the evening I'm long, in the morning I'm smallΝΎ When seen in a ballroom, I'm nothing at all.
I make you weak at the worst of all times. I keep you safe, I keep you fine. I make your hands sweat. And your heart grow cold. I visit the weak, but seldom the bold.
This food is a tortilla filled with cheese and sometimes chicken before being heated or cooked.