Hiding vegetables is one of the most common strategies parents use, and I understand exactly why. If your child will not eat vegetables, blending them into a sauce feels like a win. They get the nutrients, nobody argues, everyone eats.
My position is more nuanced than a straight no, so let me explain where the line sits.
The short answer
Generally, I would not hide foods. Children need to see what the food is actually like, as it is, rather than having it concealed.
Why it matters
Eating is a complex sensory task, and it involves all of the senses, not only taste. Sight is part of how children learn what to expect from a food.
Adults subconsciously know what to expect from foods. Children are still learning. If a vegetable only ever arrives blended into a sauce, your child never builds any familiarity with what that vegetable actually looks like, and that familiarity is part of what eventually leads to acceptance.
Put simply, hiding solves today's meal and does nothing for next year's.
Where sauces are absolutely fine
This is the nuance. It is fine to have sauces with vegetables naturally in them. That is normal cooking, and there is nothing wrong with it.
The problem is only if that becomes the only way you ever offer vegetables. If you always offer them that way, your child is never going to get used to seeing what the actual vegetable looks like.
So a tomato sauce with vegetables blended through it is fine as part of a varied approach. It is not fine as the entire strategy.
What to do instead
Keep offering the vegetable in its recognisable form
Alongside whatever else you are serving. Some children need 15 to 20 exposures to a food, and some need an awful lot more than that. Repeated offering is boring, but it is what works.
Offer it on a side plate
New foods on a side plate work well for some children, particularly those who do not like foods touching. Self serve, family style meals also help, where nothing is automatically portioned up.
Do not comment on it
If it is refused, ignore it and keep calm. Avoid the classic if you eat your broccoli you can have your pudding, because that can be perceived as pressure, and pressure tends to push children the other way.
Describe it neutrally
Talk about a food being crunchy rather than yummy. Yummy is your personal opinion, and children pick up on more than we realise.
Let them handle it
Encourage self feeding, and try not to show that you are stressed about mess. Touch is part of how children learn about food.
The vegetable group is the one most often dropped
Worth knowing: when children omit a food group, it is often the vegetable group. Children will usually still eat a couple of fruits, though not always.
That is normal enough that it is not automatically a concern. It becomes one if a child is eating fewer than 20 foods in total, or if whole food groups are missing, particularly protein rich foods, where I would want to know where their iron is coming from.
Other ways to build familiarity
Exposure does not only happen at the table. Nurseries can provide great opportunities for cooking, growing food, or exploring food through play and books. Having different cultures represented in a nursery also helps children develop curiosity about foods from different parts of the world.
The same applies at home. Anything that makes a vegetable familiar and unremarkable, outside the pressure of a mealtime, is doing useful work.
If you are worried about nutrients in the meantime
Most children need a vitamin and mineral supplement up to the age of 5, and a fussy eater might need something more depending on what is missing from their diet. It is worth getting advice on that, because supplements come in different formats and doses.
That is a better safety net than hiding vegetables permanently.
