"Delish” is another way of saying “delicious” and has been cited in print since at least 1920. Television chef Rachael Ray has made “delish” one of her catchwords, re-popularizing the word in the culinary world in the 2000s.

There are many “delish” trademarks. A food product named “Delish” was sold in 1921.


Merriam Webster’s Online Dictionary
Main Entry: de·lish
Pronunciation: \di-ˈlish\
Function: adjective
Etymology: by shortening & alteration
Date: 1920
: delicious

(Oxford English Dictionary)
delish, a.
Colloq. abbrev. of DELICIOUS a.
1920 Punch 14 Jan. 38/1 Their music, I gather, is wholly delish.
1953 ‘N. BLAKE’ Dreadful Hollow 51 Have a glass of port, won’t you? It’s rather delish.
1962 Woman 12 May 40/1 Making delish dishes for a picnic.

Google Books
14 January 1920 Punch, pg. 38, col. 1: 
Their music, I gather, is wholly delish.

6 December 1921, Salt Lake Telegram (Salt Lake City, UT), pg. 17 ad:
“Delish”

9 December 1921, Salt Lake Telegram (Salt Lake City, UT). pg. 22 ad:
DELISH
THE TWENTIETH CENTURY
WONDER FOOD
Whether breakfast, dinner, luncheon or supper—Delish proves a wonderful part of any meal. There are more than a score of ways in which it can be prepared. Delish can be served as a dessert, in place of meat or vegetables—it proves a delightful breakfast dish in place of a cereal and tastes equally good as a custard. You’ll like Delish used instead of dressing for your roast or fowl an when prepared with cheese Delish has no equal as a dinner dish.

Google Books
“Chickie" a hidden, tragic chapter from the life of a girl of this strange “today”
By Elenore Meherin
New York, NY: Grosset & Dunlap
1925
Pg. 102:
“Except a little lunch—some sandwiches?”
“That you’ll make with your little fingers? Ah — delish!”

Google Books
The stooping Venus: a novel
By Bruce Marshall
New York, NY: E.P. Dutton & company
1926
Pg. 106:
“That will be perfectly delish. I do love trains. Especially French ones.”

Google Books
Hula; a romance of Hawaii
By Armine Von Tempski
New York, NY: Stokes
1927
Pg. 38:
“Delish! Nothing gives me such joy as to see another woman fail.”

OCLC WorldCat record
You’re simply delish : from film “Those Three French Girls”.
Author: Joseph Meyer
Publisher: ©1930.
Edition/Format: Musical score : English

OCLC WorldCat record
Delish : from garden to table
Author: Neville Passmore; Trevor Cochrane; Garden Gurus (Firm)
Publisher: [Dianella, W.A.] : Garden Gurus, 2005.
Edition/Format: Book : English

OCLC WorldCat record
Delish! : the J.W. Jackson recipes
Author: Philip R Craig; Shirley Prada Craig
Publisher: Edgartown, MA (RR1 Box 65B9, Edgartown, MA 02539) : Vineyard Stories, ©2006.
Edition/Format: Book : English

Slashfood
What’s the most annoying Rachael Ray catchphrase?
by Bob Sassone, Posted Dec 11th 2007 @ 12:33PM
There are several “Rachael Rayisms” (I think she coined the term herself), and we all have our favorite. Or should I say our least favorite of all the ones we don’t like.

Mine used to be “EVOO,” but that has become such a part of the everyday food lexicon that I consider it a real food term now and not just something that Ray says (in fact, I believe the Oxford Dictionary just added it?). I’m gonna go with “Delish,” because it embodies everything that’s silly about the worst cooking shows and just overall lameness.