“Tonkatsu” (or “ton-katsu”) is a Japanese dish of deep-fried pork cutlet. The western-style dish was invented about 1900, possibly at the Rengatei restaurant in Tokyo. “Panko” (Japanese breadcrumbs) is used to bread the cutlets.
   
“‘Ton-katsu’ for pork cutlets” was printed in a 1938 book. A recipe for tonkatsu was printed in the Tucson (AZ) Daily Citizen on November 24, 1959. Tonkatsu was on the menu of many Japanese-American restaurants in the 1960s.
 
Tonkatsu is usually served with a special tonkatsu sauce. “Katsudon” is a dish that takes its name from the Japanese words tonkatsu (for pork cutlet) and donburi (for rice bowl dish). “Torikatsu” (chicken katsu) is a dish of chicken cutlets (instead of pork cutlets).
   
     
Wikipedia: Tonkatsu
Tonkatsu (豚カツ, とんかつ or トンカツ, [tonꜜkatsɯ], “pork cutlet”) is a Japanese dish which consists of a breaded, deep-fried pork cutlet. The two main types are fillet and loin. It is often served with shredded cabbage. In Korea, tonkatsu is known as don-gaseu (돈가스) or don-kkaseu (돈까스), which derived from a transliteration of the Japanese word.
 
Etymology
The word tonkatsu is a combination of the Sino-Japanese word ton (豚) meaning “pig” and katsu (カツ), which is a shortened form of katsuretsu (カツレツ), the transliteration of the English word cutlet, which again derived from French côtelette, meaning “meat chop”.
 
History
Japan
Tonkatsu originated in Japan in the 19th century. Early katsuretsu was usually beef; the pork version was invented in Japan in 1899 at a restaurant called Rengatei in Tokyo. It was originally considered a type of yōshoku—Japanese versions of European cuisine invented in the late 19th and early 20th centuries—and was called katsuretsu or simply katsu.
       
Google Books
Editorial Jottings (Volume 2)
By Inazō Nitobe and Kennosuke Sato
Tokyo, Japan: Hokuseido Press
1938
Pg. 270:
“Demo” for demonstration, “agi” for agitation, “dema” for demagogy, “anakuro” for anachronism, “pro” for proletariat, “sympa” for Communistic Sympathizers, “moga” for modern girl, “ton-katsu” for pork cutlets, “infreh” for inflation, “mora” for moratorium, are some familiar expressions.
 
24 November 1959, Tucson (AZ) Daily Citizen, “Cook’s Corner,” pg. 10, col. 5:
During their stay in Tokyo, the Bernard Silbermans, 1213 E. Spring St., became acquainted with such Japanese delicacies as octopus, squid and seaweed. But the two dishes most enjoyed by the family were Tonkatsu (deep fried pork) and CHicken Teri-Yaki.
 
TONKATSU
to make Tonkatsu, cut 4 thick pork chops into approximately 1 inch squares. Dip cut pork into 1 raw egg and cover with 1/2 cup bread crumbs. Fry breaded pork squares in deep hot oil until golden brown (about 6 minutes). Serve with boiled rice and siding of fresh, thinly shredded cabbage. Use soy sauce to taste. Serves 4.
   
6 December 1959, San Francisco (CA) Sunday Chronicle, “Dining Out; Yamato Was Imported in 7000 Tiny Pieces” by J. L. Pimsleur, Datebook sec., pg. 6, col. 5:
... Tonkatsu (a special pork cutlet—$1.65); ...
   
Olson’s Orient Guide
By Harvey S. Olsen
Philadelphia, PA: J. B. Lippincott Company
1962
Pg. 302 (JAPAN, TOKYO, Zakuro): 
Beef at its best in sukiyaki and many Japanese teishoku (table specialties) such as sashimi (raw fish), domburi (bowlfuls of rice mixed with eggs, chicken, vegetables, seafood, and eels), ton-katsu (Japanese style pork cutlets), suimono (clear soups), miso-shiru (bean-paste soup) and momo yaki (charcoal broiled chicken thighs).
 
26 May 1963, Washington (DC) Post, “Chinese Food a Specialty” by Isao Kadota, pg. K23, col.s 7-8:
Apart from raisukare, the most typical Japanized foreign dish is probably tonkatsu—which could be described on the menu of a pretentious restaurant as “Pork Cutlet a la Japonaise” and which is popular among foreigners visiting Japan.  The word ton means pork, while katsu is an abbreviation of cutlet.  But the tonkatsu is a very Japanese form of pork cutlet.
 
Most tonkatsu restaurants have a typically Japanese appearance (unlike those serving genuinely foreign food, which try to look as un-Japanese as possible).  Quite a few of them hang noren—the slit curtain hung over the doorways of Japanese restaurants—at their entrances.
 
Tenderloin of pork is used for tonkatsu and is normally sliced very thick.  The sinews are removed, the meat is sprinkled with salt and pepper, dipped into a batter of flour and beaten egg and then covered with bread crumbs. The final stage is to deep-fry it in vegetable oil. When eating tonkatsu, most Japanese flavor it with Japanese Worcestershire sauce (sweeter than the Western variety), gravy sauce, or Japanese soy sauce. Usually, it is accompanied with finely-sliced cabbage. It is fascinating to watch an expert cook slice the cabbage with amazing skill and speed.
   
15 September 1963, Sunday Star-Bulletin & Advertiser (Honolulu, HI), Aloha sec., pg. 4, col. 1 ad:
JAPANESE & AMERICAN CUISINE
SUKIYAKI, SHRIMP, TONKATSU, UDON
STEAK—LOBSTER—DELICIOUS TERIYAKI
(Oasis Restaurant.—ed.)
   
21 February 1964, Coldwater (MI) Daily Reporter, “Cook’s Tour” by Jeanne Lesem (UPI), pg. 12, col. 1:
(Nippon Restaurant in New York City.—ed.)
Among Tanaka’s other specialties are tonkatsu—deep-fried pork fillet; ...
 
Google Books
Fodor’s Guide to Japan and East Asia
New York, NY: David McKay Company, Inc.
1965
Pg. 178:
BAIRIN, Ginza-Nishi, 4-chome (tel: 561-0008). A modest establishment serving tonkatsu-pork cutlet. When done poorly, this popular Japanese dish is too frightful to contemplate, but when well-cooked from the best filet pork it is mouth-watering.
     
8 January 1965, Back Stage (New York, NY), pg. 15, col. 1 ad:
JAPAN ROOM
58 W. 56th St., New York
TERIYAKI . TEMPURA . SUKIYAKI
TONKATSU . TEISHOKU . OSUSHI
 
14 June 1968, Los Angeles (CA) Times, “Kawafuku Restaurant: A Touch of Japan in Downtown L.A.,” Dining Out Guide, pg. 19, col. 6:
(Kawafuku Restaurant, 204 1/2 East First Street.—ed.)
Shrimp tempura and teriyaki are the most popular dishes but Kawafuku’s five chefs will tempt you with a variety of offerings—yakitori, tonkatsu, katsudon, oyaku donburi and unagi donburi, to name but a few.
   
23 May 1969, New York (NY) Times, “Dining Out on Thai and Japanese Fare” by Craig Claiborne, pg. 42, col. 5:
(Tokyo-Bangkok Restaurant, 217 West 79th Street.—ed.)
There is Japanese cooking as well, but the Japanese menu on the whole seems somewhat conventional with the usual sukiyaki, tempura, teriyaki and tonkatsu or pork cutlet.
     
3 August 1969, Chicago (IL) Tribune, “Tokyo Tea Garden Tiny, but Its Food Is a Real Find” by Kay Loring, sec. 5, pg. 5, col. 1:
(Tokyo Tea Garden, 5 West Superior Street.—ed.)
We feasted in the new Tea Garden the other evening on delicious shrimp tempura in a delicately lacy batter, ton katsu [breaded pork], steak teriyaki, and osashimi [raw tuna with fresh horseradish], all of it dipped in variations of soy sauce.
 
28 September 1969, Sunday Star-Bulletin & Advertiser (Honolulu, HI), Ala Moana sec., pg. E-11, col. 4 ad:
TONKATSU
(Deep Fried pork cutlets.)
(Miyaku Delicatessen, Ala Moana Center.—ed.)
 
YouTube
Tonkatsu (deep fried pork) Recipe - Japanese Cooking 101
JapaneseCooking101
Published on Mar 28, 2012
This video will show you how to make delicious Pork Tonkatsu (deep fried pork) right at home!
Full recipe here: http://www.japanesecooking101.com/ton...
 
YouTube
#tonkatsu #porkcutlet #pork
How To Make Tonkatsu (Japanese Pork Cutlet Recipe)
TabiEats
Published on May 9, 2017
Tonkatsu is one of the most popular Yoshoku dishes here in Japan and everyone loves it. This pork cutlet is light and crispy on the outside and tender on the inside. Serve with tonkatsu sauce and a side of shredded cabbage. Subscribe! http://goo.gl/18SB8p