Amy,
 
I've found most toddlers prefer to start with white soft meats like plain
fish and chicken.  Have you tried those?  It took forever before my daughter
would eat beef.  Ends up beef has a lot of allergy potential...I think these
kids are smart by instinct!
 
Also, next time you are at the grocery, look at the protein content of
formula, and you'll see it isn't all that high.  Even breastmilk isn't that
high in protein either.