Even if you are not a foodie or are staying in a hotel rather than an apartment with a kitchen, you might like to explore one or more of the outdoor street markets of Paris. Our favorite is the Marché Bastille, which starts at the Place de la Bastille and continues for a couple of city blocks down Bld. Richard Lenoir. The big day is Sunday, in the morning till around noonish. There is a jaw-dropping array of food and other items. There are other markets as well.
Food markets in Paris. The first market listed on this site, Rungis, is the main drop for all food coming into Paris. I think you have to have a guide to get in, and they go around 4:30 a.m., so we've never been.