“So dumb you need a half hour to cook Minute Rice” (food joke)

Minute Rice is a trademarked product that was introduced in 1949. It takes a few minutes to make Minute Rice, not necessarily just one minute.
 
“So dumb/stupid you need a half hour (or hour) to cook/make Minute Rice” is a food joke that dates to at least 1958. The joke has been used in “yo momma” joke collections, often with the extended time it takes one to watch the television show 60 Minutes.
 
A similar food joke is “So dumb you need the recipe for ice.”
 
   
Wikipedia: Minute Rice
Minute Rice is a brand of instant rice. The product was introduced in 1949 by General Foods, who merged with Kraft in 1990 and became Kraft General Foods, which became Kraft Foods in 1995. The product recently was sold to Riviana Foods (part of Ebro Puleva) in the United States, and to Ronzoni Foods Canada Corporation in Canada.
     
24 March 1949, Hutchinson (KS) News-Herald, pg. 20, col. 1 ad:
Easy to Cook
Minute Rice...5 1/2-oz. Pkg. 14c
(Safeway—ed.)
 
Google News Archive
25 March 1958, Miami (FL) News, Earl Wilson syndicated entertainment column, pg. 9B, cols. 1-2:
WISH I’D SAID THAT: Taffy Tuttle’s such a miserable cook that it takes her an hour to cook minute rice.
       
2 February 1963, Danville (VA) Bee, “Radio Ramblin’s from Danville’s Leading Station (WBTM), pg. 11, col. 7:
ACCORDING TO TOM MOORE…I don’t want you to think that my wife is a horrible cook…but she’s the only gal in our neighborhood who takes an hour and a half to make minute rice.
 
Google Books
The Giant Book of Insults:
Incorporating 2000 insults for all occasions and 2000 more insults
By Louis A. Safian
Secaucus, NJ: Citadel Press
1967
Pg. 51:
It takes her an hour to cook Minute rice.
 
Google Books
Joey Adams’ Encyclopedia of Humor
By Joey Adams
New York, NY: Bonanza Books
1968
Pg. 249:
It takes her an hour to cook minute rice.
   
Google Books
Thumbs Up:
The life and courageous comeback of White House press secretary, Jim Brady
By Mollie Dickenson
New York, NY: Morrow
1987
Pg. 388:
Other Reagan lines he (Jim Brady—ed.) provided: “It takes the Congress two months to make minute rice.”
 
26 June 1989, Newsday (Long Island, NY), “A Funny Bone of Contention” by Marilyn Goldstein, pg. 6: 
Danny: “My Mom is so stupid it takes a half hour for her to cook Minute Rice.”
Peter: “My Mom’s so stupid she can’t make ice. She forgot the recipe.”
     
Google Books
Talkin That Talk:
Language, culture, and education in African America
Geneva Smitherman
London: Psychology Press
2000
Pg. 227:
Yo momma so slow, it take her an hour to cook Minute Rice, two days to watch 60 Minutes, and a year to watch 48 Hours.
 
660 News (Calgary)
Reagan spokesman wounded in assassination attempt fights on for gun control, presses Obama
Jim Abrams, The Associated Press
Mar 30, 2011 19:01:55 PM
WASHINGTON - Jim Brady, President Ronald Reagan’s smooth-talking press secretary, has not stopped speaking his mind, forcefully and poignantly. He made that clear from the Capitol to the White House Wednesday on the 30th anniversary of the assassination attempt that paralyzed him.
(...)
The Bradys said Obama expressed agreement with their goals but said he has learned since coming to Washington that things take time.
 
“It takes two years to make minute rice,” Brady said he told Obama about the pace of progress in Washington.