What does “maison” mean after a food word in French?

You already know maison means “house.” But put it right after a food word and it changes meaning: it now says the food is homemade. So sauce tomate maison is homemade tomato sauce, and confiture maison is homemade jam. One useful detail: in this use, maison never changes form. It stays maison for one jar or many, masculine or feminine. You will see it on market stalls and menus all the time.

In the clip the speaker walks past the home-cooked goods: “Il y a des produits maison, des cornichons, des sauces tomates maison.” — “There are homemade products, pickles, homemade tomato sauces.” Normally maison is a noun (“house”) and une maison is feminine. But placed after a food noun, maison works like an adjective meaning “made at home, not factory-made.” It is invariable here: des sauces maison, une tarte maison, des plats maison — the word never adds an -s or an -e. On a restaurant menu you may also see la spécialité maison (the house special) and the longer form fait maison (“made in-house”), which France even regulates as an official label. Related market words from this clip: un produit local (a local product), un producteur / un paysan / un agriculteur (a farm producer / farmer), and un marché paysan (a farmers' market).