Why does she want to use a light tent for this?
A light tent is a good choice for quick and easy photos that are bland and simple but they don't show the product - in this case food but it applies to most things - a their best, so I would guess that a chef would want something much better. They are useful for purely functional items such as workboots where good detail is essential but making the product look its best isn’t worth the extra effort / cost of better photos.
If she really does want to use a light tent then ideally there should be at least 6" of space each side of the subject, so a 20" wide one would only allow for subjects up to a maximum of about 8".
Light cubes are the "new" light cubes, mainly because they have built in lighting, look more modern and work out cheaper because there is no separate lighting to buy, but only the best of them have extra, adjustable lights that produce fairly even lighting - the cheaper versions only have light above, and the results from these are poor. Light tents, with external lighting arranged with care, produces much better results.
If she wants good lighting with a full colour spectrum then she will need flash. Neither LED nor fluorescent lights have a full colour spectrum and, where a CRI is stated, it's usually false.
But, if she's going to get flash to produce better colour rendition then it would make sense to use just the flash, with suitable modifiers, and to forget about the light tent.