Of American-English origin, the expression cauliflower ear designates an ear permanently deformed as a result of injuries from repeated blows, as in boxing.
—Cf. also the expression glass jaw.

The expression cauliflower ear occurs, for example, in Mum is living in fear of her ex, by Jeremy Culley, published in The Bolton News (Bolton, Greater Manchester, England) of Saturday 4^th April 2015 [page 14, column 3]:

A VICTIM of harrowing domestic abuse says she is scared to leave her home—in case she sees her violent ex-partner.
[…]
Her injuries sustained in different incidents include black eyes, bite marks, bruises, cauliflower ears and cuts.

The earliest occurrences of the expression cauliflower ear that I have found are as follows, in chronological order:

1-: From an account of a boxing match between George La Blanche, ‘the Marine’, of Boston, Massachusetts, and Jack Files, of Chicago, Illinois—account published in The Boston Daily Globe (Boston, Massachusetts, USA) of Thursday 1^st December 1887 [Vol. 32, No. 154, page 3, column 6]:

La Blanche feinted and broke ground, coming up on to Files at close quarters with his dexter mawley at play on the Chicagoan’s ribs. Then there was a hustle on the ropes, and La Blanche cross-buttocked Files, who fell in the centre of the ring. He arose and swung his right on to La Blanche’s neck, and the marine staggered and uttered a loud “ugh.” He steadied himself and then went at Files, whose “cauliflower” ear was pounded in great shape.

2-: From The Cincinnati Enquirer (Cincinnati, Ohio, USA) of Sunday 8^th April 1888 [Vol. 46, No. 99, page 10, column 8]:

MACON’S MELANGE.
He Compares Old-Time Fights
With the Present Style of Using the Hands.
[…]
CORRESPONDENCE OF THE ENQUIRER.

New York, April 6, 1888.
[…] The old way was hard not only on noses and features, but on constitutions as well. The new style plays havoc with hands and cauliflower left ears, but it rarely entails lasting bodily injury.

3-: From a portrait of the Irish-born U.S. boxer Nonpareil Jack Dempsey (John Edward Kelly – 1862-1895), published in The Cincinnati Enquirer (Cincinnati, Ohio, USA) of Sunday 27^th January 1889 [Vol. 47, No. 27, page 12, column 1]:

Although Dempsey has met and defeated fifty men in the ring, he has not a mark or a scratch on his face. The cauliflower ears and broken noses which mark the phiz of so many “fighters” is missing in Dempsey’s case. This is proof conclusive that Dempsey administered punishment and never received any in return.

4-: From a portrait of the British boxer Jem Smith (1863-1931), published in the San Francisco Chronicle (San Francisco, California, USA) of Friday 8^th November 1889 [Vol. 1, No. 116, page 8, column 5]:

He seems as strong as a bull and looks as if he could stand a beating with a club. He has a cauliflower ear that lays over Paddy Gorman’s for size and architecture, which he got in his fight with Jake Kilrain.

5-: From an account of a boxing match between Billy McCarthy, of Australia, and Denny Kelliher, of Boston, Massachusetts, published in the San Francisco Chronicle (San Francisco, California, USA) of Thursday 21^st November 1889 [Vol. 1, No. 129, page 8, column 1]:

The first round was marked by a number of strong leads by the Australian and vicious right-hand swings by Kelliher, the latter, however, failing completely to land on the prominent cauliflower ear of his adversary, who ducked in time to let the compliments pass without effect.

The French expression oreille en chou-fleur is a loan translation from English cauliflower ear. The earliest occurrences of this French expression that I have found are as follows:

1-: From Culture physique et cures d’exercice (myothérapie) (Paris, France: Masson et C^ie, éditeurs, 1913) [page 489], by Dr Francis Heckel.

2-: From L’Auto (Paris, France) of Wednesday 5^th March 1913 [No. 4,524, page 1, column 4]:

Chaque métier a ses marques et ses déformations. C’est ainsi que le pianiste se reconnaît à l’aplatissement des doigts et le boxeur à ses oreilles en « chou-fleur ».
     translation:
Every job has its marks and its deformations. Thus the pianist is recognisable by the flattening of his fingers and the boxer by his “cauliflower” ears.