model the behavior you want kes to do. YOU eat it

make a big deal out of how yummy it is and don't share. now i know you said kes will eat it but only if you hold it. i'll sometimes hold food for our flock if they are resistant to eating it from their dishes. but only for a second

i let them get a taste then back to their dish it goes.
you can also experiment with different temperatures and textures. my CAG prefers his people food to be more lukewarm than warm and will let his dinner sit until it's almost cold. the quakers dig in right away. some foods are more readily accepted raw, some cooked. some more readily accepted almost pureed, some need to be chunkier. some warm, some cold. you get the idea.
just keep at it and i'm sure kes will be more accepting of whatever you offer eventually. louie never used to trust anything i offered. but eventually he realized mama didn't give him ickies, and now he will at least try everything i offer before throwing it away.
kris