In Mark 7, how did Jesus cure the deaf man with a speech impediment?

By putting his fingers in the deaf man's ears, and his spit on the deaf man's tongue

He took him aside from the multitude, and put his fingers into his ears, and he spit, and touched his tongue. ...

And straightway his ears were opened, and the string of his tongue was loosed, and he spake plain. Mark 7:33-35