Do you have picky eaters in your house? I do. Even when I chop onion as small as humanly possible they can find it in a mouthful of food, pull it out & say "I don't like this, why did you put onion in it?".
But I have found a solution for my home, where the adults really like onion, & the children don't: dried onion flakes. Here is my not-so-secret recipe for the most delicious meatballs/rissoles [I give this recipe out often because people always comment on how tasty they are].
Now there are no exact quantities, just rough guidelines, each time I make them they're slightly different.
Place in a bowl:
mince [I use low fat]
dried onion flakes [a teaspoon or two depending how much meat]
a splodge of tomato sauce
a dash of sweet chilli sauce
freshly ground salt & pepper
an egg to bind it together
Now put your disposable gloves on & mix it all together with your hands! Disposable gloves are essenial in any kitchen for making meatballs, cutting up yukky stuff like chicken, making pastry & stopping it getting under your fingernails etc etc.