Give them to him earlier when he is 'really' hungry. Kids often have a hungry window of opportunity in the afternoon between 3 -4.30 (this happens to be the time of day when we best absorb nutrients!) feed them veggies and rice then, and then part of the family meal when you eat later on. Also juicing veggies for a mid morning snack, carrots, beetroot, spinach, parsley and some fruit to sweeten it, kids love it and it's a nice boost before lunch.
Make sure you are not missing his hungry period and filling him with snacks trying to stretch him to dinner.
If you don't want to hide them exactly, can you make them a part of the meal instead of a side? It also might mean they have more flavour then too... For example a stir fry, curry or even Spag bog but with chunks of veggies?
Another idea - could you offer some veggies on their own first before adding the meat?
Yes there's definitely that hunger window, that's when my DD actually eats cooked carrots.
In find she eats well when the veggies are soft and in a sauce, like a casserole. I squish it into the rice. Eggplant is great for this, even beans. Sometimes she eats raw mushroom pieces while I'm cutting them.
My DD also loves pumpklin soup or lentil soup, it's the novelty of dunking the bread in that makes it fun for her. And you can obviously puree anything into the soup.
I grate veggies into things for my older kids. Mash potato comes with pumpkin or sweet potato mashed in as well. Lasagna has grated carrot at least in it.
DD2 & DS have just started to realise they like carrot, after I told them I was secretly mixing it in (could've gone the other way though!)
DD3 will eat everything in a mixed dinner, but won't touch the veggies alone. She'll eat stirfry, pasta dishes, cassaroles etc & eat everything on the plate, but meat & 3 veg & the veg doesn't get touched, so maybe try those types of meals?
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