The food was fair to middling.
middling
/ˈmid-liŋ/
adjective
of middle, medium, or moderate size, degree, or quality
mediocre, second-rate
of, relating to, or being a middle class
noun
any of various commodities of intermediate size, quality, or position
a granular product of grain milling; especially : a wheat milling by-product used in animal feeds
idiom
just average : not especially good