Sentence:  Fry in butter a small minced onion , <WSD>rub</WSD> with a tablespoonful of flour , add half a cup of cream , six beaten eggs , pepper , celery salt , a teaspoonful of minced chives , a dash of cayenne , and a pinch of nutmeg . 
Meaning of the word marked with <WSD> tags:  move over something with pressure