If you don’t have time to slog through detailed research manuscripts, this roughly 2 page synopsis of the the ginger exosome-like nanoparticle paper is a quick read.

I posted about the research paper here: https://www.cell.com/cell-host-microbe/fulltext/S1931-3128(18)30523-7 and @FP posted a grape exosome-like nanoparticle paper here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3702113/

Since microRNAs are RNA and therefore not terribly stable, I doubt they have even the slightest chance of surviving cooking, or sitting around at room temperature for an extended period of time. At least once they exit the plant cells.