food/facotry tours in NYC
I don't think there's really any factories big enough in Manhattan to really accommodate people touring them. Maybe Beecher's Handmade Cheese when it opens, but I believe the idea is to have the entire cheese making process visible from behind glass, but not have patrons walking around.
But if your interest is in seeing the making of things exposed, visit Jacques Torres shop in Tribeca, as well as Amy's Bread in the Chelsea Market. The other locations don't have the machinery/ovens/etc. exposed.
As for food walking tours, Manhattan is a great place for those:
Try also RGR's famous self-guided eating tour of the LES.
Note two changes: Guss's Pickles has closed, so substitute The Pickle Guys, on Essex off Grand. And the correct address for Economy Candy is 108, not 145.
You should consider posting your factory tour request on the Outer Boroughs board.
Here are some neighborhood exploration ideas for the Outer Boroughs:
My Flushing walking tour is towards the bottom here:
You can take the LIRR from Penn Station to Flushing in about 20 minutes. More expensive than the subway but worth it.
If you want to stay in Manhattan, try scoopG's self guided Chinatown tour:
350 Hudson St, New York, NY 10014
49 Essex St, New York, NY 10002
250 Bleecker St, New York, NY 10014
108 Rivington St, New York, NY 10002
As always, my thanks to kathryn for suggesting my tour. :)
Though Streit's Matzos isn't included in the current version of my tour (I'm working on a revised version), I believe they offer tours which allow you to see the matzohs being produced, and you get a freshly baked matzoh to taste at the end.
148 Rivington St, New York, NY 10002