I'd go with Bobbo's suggestion - glue and clamping, vacuum bag would be ideal.
The issue with that is that I can't imagine the wood is ever going to be properly straight again regardless of any clamping.
Wouldn't it be better to get some reclaimed elm cut to size and reglue? I'm planning on refinishing the rest of the table anyway
@dbr started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
I'd go with Bobbo's suggestion - glue and clamping, vacuum bag would be ideal.