The register
The register lists Siass Catering Limited in London as a licensed sponsor on Skilled Worker, an entry that goes back to at least 2026. Its rating on the register is Worker (A rating).
Siass Catering Limited is the registered name (Companies House number 14340192), a private limited company on the register since 2022. The registered office is at 4 Pinchin Street, Pinchin Street, London, E1 1SA, E1 1SA. Its filed activity puts it in hospitality.
A licence says an organisation may sponsor; it does not say it is hiring today. The way to find out is the same as for any employer: the careers page, the job boards, and a direct approach with a UK-style CV that says early that sponsorship would be needed.