In Traditional Chinese Medicine, there is a theory that after sickness, your body becomes “cold,” so eating certain foods can strengthen and warm your body.

We Taiwanese usually eat congee because it is easy to digest and gentler on our bodies.

NIGGA

We Taiwanese usually eat congee because it is easy to digest and gentler on ourthe bodies.

Best to use "the" instead of "our" because congee being gentler on the body is more like a general description rather than something specific.

After recovering from an illness, some people havuse herbal tonics, like sesame oil chicken soup, to help their bodies recover.

The end of this sentence implies using the herbal tonic so it's best to put "use" instead of just describing them as "having" it

In Traditional Chinese Medicine, there is a theory that after sickness, your body becomes “cold,” so eating certain foods can strengthen and warm up your body.

We Taiwanese usually eat congee because it is easy to digest and gentler(r) on our bodies.

Since you haven’t said what you’re comparing it to (e.g., “gentler than this other food”), it’s more natural to say it’s “gentle,” but “gentler” isn’t wrong.

After recovering from an illness, some people have herbal [tonics | restoratives], like sesame oil chicken soup, to help their bodies recover.

A tonic is a restorative drink. Since we don’t “drink” soup in English, it sounds odd to describe a soup as a “tonic.” You could call it a “restorative” (noun).

In Traditional Chinese Medicine, there is a theory that after (recovering from) sickness, your body becomes “cold,” so eating certain foods can strengthen and “warm” your body.