I like the idea of hiding and getting more in. I'm really not a great cook or know a lot about what I can do with food so any more ideas on ways I can hide food to get more in him would be great
I started off the book Deceptively Delicious by Jessica Seinfeld, where she basically cooked up a batch of purees and then added them to other foods. I wouldn't exactly recommend this book, because I think the nutritional value of a couple of teaspoons of overcooked veg is completely off set by the amounts of sugar and fat that are used. But it does have some good tips on which flavors will mask each other. And it might be a good place to start if you need recipes to follow.
Even though mine are now quite good eaters I still use some of the tactics that I had to rely on during the fussy phase (my son was one of those who didn't come out of it but just got worse and worse). I make a smoothie every day with both fruit and veg and hide a vitamin supplement or iron supplement if it's needed.
Combinations include
kiwi, pineapple, half an avocado, half a cup of spinach and apple juice to thin
strawberries, carrot (slightly softened) and orange juice
apple, pear and spinach with apple juice
mixed berries, half a beetroot (cooked and not in vinegar!), yogurt
(you can get lots of fruits and veg for the freezer so the smoothies end up nice and chilled)
Bananas are brilliant! You can make "ice cream" by slicing up a nice ripe banana, lay it out on parchment and freeze. Then just blend the frozen slices until creamy. Eat immediately - it doesn't store. They're happy cos they are eating ice-cream, and I'm happy cos they're eating fruit.
Bananas are a very strong flavor in anything you bake and will mask other vegetable flavors well. So banana muffins/ or banana bread were a staple in my house for ages. DH still peers suspiciously at anything I bake in case there might be something healthy lurking in there!
Some people swear by cheese sauce and can serve anything as long as it is doused in it. Didn't work for me unfortunately.
I still add tomatoes, onions, carrots and peppers (chopped, grated or zapped in the blender) into mince dishes. I put parsley into almost everything savory (though that's really for my DH cos he's terrible for not eating any greens!)
Most people worry about kids getting enough protein but the requirements aren't that high and are probably well met if the child is drinking milk. It's present in a lot of foods that you wouldn't necessarily think of as protein sources. Iron however, is important, and you might want to either look at a supplement or using one of the follow on toddler milks for that. For long term fussy eaters magnesium can be a big factor. That really helped us. when you are low in magnesium it can leave you craving bland food, or having a very small appetite. But obviously that's a discussion to have with someone qualified in nutrition.
hope that helps some