How To Move Part of an Established Site to a New Domain

I intend to move one language of this website onto a new domain. I was thinking to do 301 redirects from all old pages to all new pages and of course update the sitemaps accordingly. This way, Google should understand that my pages changed location and will index the new ones. But, it will probably exclude my webpages from SERPs, at least for a period.How can I do this move, in order to make it as painless as possible for my site?