Neither of my DSs are lovers of vegetables..
I batch cook a lot. For any tomatoey based sauce I add carrots, onions (red and white), mushrooms, courgettes, garlic, extra tinned toms, tom puree & peppers. I chop these in a pampered chef chopper, but have pureed in the past. This gets made into lasagne, spag bol, chilli or mediterranean chicken/pork dishes.
Stews are also good for hiding veg. Parsnips, carrots, swede, onions, peppers...
My other options are baby corn, corn on the cobs, peas, school bars, raisins, fruit juice, smoothies, houmous, baked beans, spaghetti hoops with hidden veg (Heinz), frutapura in porridge, carrot cake, sponge cakes with lot of apple in the mixture, nuts & seeds... (I've been doing this for years!)