Huge Spanish spring onions

Hola happy gardeners, I found the big spring onions in consum, and like them very much, but I have asked everyone selling them, even garden centre In Mazarrón, where can I buy the seed for them and what variety are they, but no one knows or won’t tell me, at the moment I am trying to grow one in pot from root, which I successfully do in Uk 🇬🇧, so hoping this will do the same and then go to seed, but if anyone knows what variety they are and where I can get the seeds, I would be very grateful, as can only have them when over, and then return to Uk in car, but next trip will be last one by ferry and will be flying from them on,