The Goofs belong to a co-op, which means that over the summer we get fresh vegetables in bountiful quantities. Although the co-op folks get very excited about how delicious and invigorating these fresh veggies are - the kids don't buy it. It ain't cookies.
Fortunately, there are other aspects to vegetables for kids to love.
My son discovered that he rather liked roasted beets. But he liked them even more later that evening, as he ran around the house yelling, "Pink pee! Pink pee!"
Yes, beets have a certain impact on the digestive system. My son now wants to eat beets at every meal so he can show his friends.
Now we just make up effects, "Cabbage, orange pee - but you have to eat a lot of it!"
When the vegetable fails to have the expected effect, we can always fall back on, "I guess you didn't eat enough."
Keep some food coloring hidden around the bathroom so you can provide encouraging examples...
"Daddy ate all of his rhubarb and and it made a rainbow." The downside of course is that for this to be credible, I actually have to eat rhubarb - the mutant celery.
My daughter found she liked fennel. I mean, really liked fennel. When I say she ate a fennel salad, it was literally that - just a big pile of fennel.
She was pooping good'n plenty for the next three days.