Definitely the "hide the vegies in the spag bol trick" - you can put almost anything in - I will generally "hide" 4 or 5 vegies at a time. Finely diced mushies etc.

I also puree brocolli to put in the egg when crumbing chicken - you can't even tell and it actually tastes better - the boys call it "magic skin". Even DH who hates brocolli loves it and he knows it's there!

I also put grated carrot and corn kernels (as well as onion and zucchini) in zucchini slice - which DS1 won't eat if it's called zucchini slice, but he loves egg and cheese pie

We often eat orange potatoes - pumpkin and potato mashed together. This is an old family recipe from DH's family - so called because DH wouldn't eat it if it was called anything else (can you tell who DS1 takes after ).