recognize (someone or something) by (something)
To be able to identify or remember someone or something because of some distinguishing trait, characteristic, behavior, etc. I was able to recognize him by the unmistakable mark on the right side of his face. You should be able to recognize their house by the large Italian flag they always have hanging from their front porch.
recognize someone or something by something
to know someone or something by some distinguishing sign. You will be able to recognize me by my long mustache. Mary recognized her car by the ribbon tied to the antenna.