Based on an idea provided by PPKer, birdsonawire, I've started freezing pureed fruit concoctions in baby food jars. Andy and Emerson spend a good 2o minutes enjoying the "pupsicles".
Andy and Emerson go gaga over these things.
I'm sure they wouldn't discriminate against veggies, but so far I've used various mixtures of leftover bananas, apple sauce, silken tofu, and soy milk.
I'm still looking for a vegan dog chew that'll last longer than dehydrated sweet potatoes! Found some in the UK, but shipping is astronomical.