I was at a restaurant yesterday and I was surprised to get young onions (sorry for the direct translation from French oignon nouveau en botte - I added a picture below) cooked as whole, but melting once they are cut.
What I got on the plate was just the head (without the green part), cooked but not fried/braised (the head was white). When cutting it, the layers fell apart and the taste was almost sweet, without any aggressive onion taste. If I did not look closely at what I was eating I could miss the fact that it was an onion.
What would be the right approach to cook an onion like this? Boil it and then sauté? Cook it in butter for a long time at a low temperature?