Betta are mostly carnivores, and aside from the occasional peas, I've never seen them show interest in veggies... (well, they love snello, but who doesn't?
)
I'd cut the veg into chunks or slices, skewer with a fork to weight down. I've also frozen slices and thawed in a small bit of water in the microwave, sinks easily. I'd be very surprised if the betta showed interest.

I'd cut the veg into chunks or slices, skewer with a fork to weight down. I've also frozen slices and thawed in a small bit of water in the microwave, sinks easily. I'd be very surprised if the betta showed interest.