Gastronomic rhymes with:
autonomic, economic, ergonomic, macroeconomic, microeconomic, noneconomic, socioeconomic, technomic, uneconomic, adamec, adamik, atomic, autonomic, comic, diatomic, economic, ergonomic, islamic, macroeconomic, microeconomic, monatomic, noneconomic, romick, socioeconomic, subatomic, technomic, tomich, tragicomic, uneconomic
Gastronomic sounds like:
gathering, gatherings, gesturing, guttering