“When is an Irish potato not an Irish potato?”/“When it’s a FRENCH fry!”

An Irish potato riddle is:
 
Q: When is an Irish potato not an Irish Potato?
A: When it’s a FRENCH fry!
 
The joke has been cited in print since at least 2003.
 
   
Google Books
Let’s Celebrate St. Patrick’s Day
By Peter Roop and Connie Roop
Illustrated by Gwen Connelly
Minneapolis, MN: Lerner Publishing Group, Inc.
2003
Pg. ?:
When is an Irish potato not an Irish potato?
When it’s a FRENCH fty!
 
Google Groups: alt.humor.puns
Jest For Kids Weakly 03-16-04
Stan Kegel
(...)
When is an Irish Potato not an Irish Potato?
When its a French fry. (Candy Silver)
   
Twitter
Shamrock‏
@Shambo
Shammy’s Joke de Jour: Q: When is an Irish Potato not an Irish Potato?  A: When it’s a French Fry.
12:04 PM - 1 Mar 2009
 
Twitter
JustGoneSystems‏
@RichardsProClng
When is an Irish potato not an Irish potato?  Answer:  When it’s a FRENCH Fry!
8:52 PM - 17 Mar 2009
 
Facebook
‎Kathy Cummings‎ to Ellen DeGeneres
March 17, 2014 ·
When is an Irish potato not an Irish potato? When it’s a French fry!
 
Google Books
Food Jokes For Kids 4
By Peter Crumpton
PeteyRF Creative
2015
Pg. ?:
When is an Irish potato not an Irish potato?
When it’s a French fry!
 
My Town Tutors
St. Patrick’s Day Jokes: Top 10 St. Patrick’s Day Jokes
Posted on March 17, 2015
(...)
16. When is an Irish Potato not an Irish Potato? …. When it’s a FRENCH fry!
 
Google Books
1001 Kid’s Jokes
By Kay Barnham
London: Arcturus Publishing
2016
Pg. ?:
When is an Irish potato not an Irish potato?
When it’s a French Fry.
 
Twitter
Alana 🍀 ❤️ ⚾️ 💙‏
@airalana24
When is an Irish Potato not an Irish Potato?😳🍀
When it’s a FRENCH fry! 🍟😁😜😆😂 #cornyjokesarethebestjokes
8:25 AM - 5 Mar 2017 from Pennsylvania, USA