Get a copy of Deceptively Delicious by Jessica Seinfeld.
As someone above mentioned, you can sneak purees of healthy veggies into foods in lots of different ways. Her book is filled with lots of great recipes (she even puts spinach into brownies and they’re fantastic).
The other thing to keep in mind is that it takes an average of 5–6 exposures to a food before kids develop a liking for it so just because he rejects something doesn’t necessarily mean that he will never grow to like it.
Foe the next year or so, just focus on sneaking as much nutrition into him in whatever way you can accomplish it.
Once he is a bit older and you can reason with him, then you might want to consider establishing a policy of ONLY ONE bite is required of whatever is being served.
This way he gets multiple exposures to new foods and one bite is a bearable requirement. Just one bite won’t kill anybody.
That’s a policy which has worked for a lot of people because it prevents these constant battles over an entire meal. And once that one bite is sampled its over with and he can eat what he wants for the rest of the meal.
Eventually his palate will expand over time.
Another thing to do when he’s a little older is to involve him in helping you with preparing meals (and growing a veggie garden if possible) since being involved really increases a childs eagerness to eat what’s been prepared.
This is what Lydia Bastianich did with all of her kids growing up and now does with her grandkids as well but one doesn’t have to be a chef to employ the same psychology of making foods of a great variety enjoyable and something to look forward to.
If eating is perceived as a constant battleground and control issue, kids use that to try to exert control. But if it’s just an everyday time of family togetherness, then kids don’t tend to have exaggerated issues with food.
But in avoiding a battleground, you can’t just totally give in and let them eat whatever junk and crap they want to. It’s striking a balance with some minimal requirements that hopefully ends up with a child who can appreciate a variety of foods and enjoy them.
Just think of the picky toddler years as a temporary phase which they’ll eventually outgrow as long as they’re not allowed to remain stuck there. You need to give them those 5–6 exposures to each food in order for them to know what they truly like or dislike rather than leaving them stuck in whatever phase they’re in. The trick is to do it without making the dinner table a constant battleground.