"characteristic expression" is correct and usable in written English.
You can use it to refer to a statement, action, or behavior that is characteristic of a particular person, situation, or thing. For example: "She had a characteristic expression of joy on her face."
A characteristic expression?
She flashed the smile of reassuring optimism that is probably her most characteristic expression.
Mr. Arafat repeatedly parried questions with his characteristic expression, "Not to forget".
Ragtime found its characteristic expression in formally structured piano compositions.
I had suggested that political opposition in Damascus often seemed more gestural than real, and that making movies no one could see was therefore a characteristic expression of Syrian dissent.
Before Rosh Hashana last year, the cardinal issued a characteristic expression of sorrow for wrongs that he and fellow Catholics had done to the Jewish people, a statement widely publicized and welcomed by Jewish leaders.
"Remedies" proposed for under-age drinking are a characteristic expression of this: raise the drinking age, make drinking more expensive, prevent the sale of cheap drink in supermarkets and petrol stations.
The cooperation of ecclesiastical discipline and state legislation found its characteristic expression in the United States in the Prohibition amendment to the Constitution.
Film makeup differs significantly from that of the stage, where heavy lines are required to convey a characteristic expression to the audience.
Despite Dufay's developments in the mass as a musical genre, the polyphonic chanson, or secular song, is the most characteristic expression of the Burgundian school.
This age of gods was succeeded by an age of heroes and finally by an age of men, whose characteristic expression was prose and whose inevitable trope was irony.
