I wish you had asked before you pulled them up. At this point, I'd say prepare them anyway you like and enjoy them. I always grow my onions from seed. They are much less likely to bolt. If I start them in the house in March, plant them out in May, by September I'll have very nice baseball sized onions.

Gosh you must have enjoyed lots of nice salads with such a good crop of spring onions! I think I'd be inclined to pickle them as I'm not sure they will keep through the winter to use as sets.

I'd chop them fine and freeze them and use in stir fries etc. they wont become a proper sized onion even if they do remain sound. they are a different variety to what I call cooking onions.