I am Stumped

She only eats things that start with a capital letter (ha!)

My more serious solution that she only eats things with two vowels or less under the following conditions:

i) one vowel words must have the vowel as the third letter

ii) two vowel words must have a vowel as the second letter

that won't work
corn and lamb both only have one vowl
and the vowles are bothin the same place

It does work because she doesn't eat either because the vowel isn't the third letter

Joanne eats... Joanne doesn't eat...

L-Losbster L- Lamb
P-Pears P- Potatoes
C- Crab C- Corn
They all match and cancel ?
Things that didn't match up ?
T-Turnips S-Spinach
A- Apples
Use the beginning letters of the foods that don't match up, and spell them ? S.A.T. =

SAT is this what Joanne... did ?

Here's one I like:

Joanne only eats a food if the singular form of its name ends with a consonant preceeded by a vowel.

(e.g. turnips -> turnip, eaten because of "ip")

is it because she ordered a lobster, pair, turnip and crab pie?

Beacause Joanne doesn't shrimp.
SHe does not like apples.
SHe hates spinach.
And She despises potatoes, corn and lamb.