I kept reading about how much flavor is imparted in a good soup with the addition of a parmesean rind. Great!
So I bought/kept some and now can’t seem to find any good recipes that call for them. What are the rules? Only cream based soups? Or will tomato based ones work fine? How long do you keep the rind in the soup itself?
Of course, sharing your recipes which benefit from the added rind or two will certainly help 
Minestrone, Italian Wedding, and similar broth-based soups are the ones that improve most from having a parmesan rind simmered/steeped in. I think with cream and tomato based soups it’s better just to sprinkle in grated parmesan.
Unfortunately I don’t have any recipes- my soup making is normally confined to doctoring up ramen packets and canned soups- so this is all based on what I’ve read in cookbooks and blogs/seen on cooking channels.
I put them in all my chicken broths, and add them at the beginning, as soon as I skim the scum. My local produce market sells them cheaply, and I throw them in the freezer. No need to thaw before I put them in the pot. Also do not need to add salt as parmesan is pretty salty.
I agree with pretty much everything Leiko said.
THIS! I came to say minestrone. It is *absolutely awesome *with reggiano rinds in it. And I also agree about tomato and cream based soups being better with a grating of parmiggiano rather than using the rinds.
OK, so, does the rind kind of melt into the soup, or do you fish it out when it’s done?
You take them out as they will not completely melt in a simmering pot of soup. Or at least ladle them out prior to serving. You can leave the rinds in with any leftovers for storage.
For me it works best with spicy tomato soup. But I put the grated parmesan into it right before eating it, not while cooking it. Mmmmm.
Do you make your own stocks??? If I have a parm rind available, I put them in when making chicken stock. I’ve never made a beef stock though.
Cut casings off of some good italian sausage. Make tiny meatballs out of just the sausage (about the size of a wad of gum… little). Chop the kale into pretty small pieces. Dice the onion. Sweat the onion in some olive oil, with about a clove of minced garlic. Add the meat balls. Roll them around until they get just a hint of color. Add in the chicken stock and bring to simmer. Add in the parm rind, beans, and kale. Simmer for 20 minutes. Add in your pasta of choice. Simmer until pasta is done.
**Sigmagirl **and llcoolbj77, I’ve only made stock once, and it was turkey stock for the gravy at this past Thanksgiving’s dinner, which was amazing. So the next time I plan to make a soup (I think I’ve only made one this whole winter!) I intended to make my own stock. I’ll be sure to throw a rind in there (probably later this week). Is more better? foiegrasisevil, could I use two rinds or would that be overkill?
Leiko, which blogs do you read?
Oh, gosh, so many cooking blogs!
I check the following pretty regularly:
The Pioneer Woman Cooks
Tasty Kitchen
Not Quite Nigella
Homesick Texan (mostly Tex-Mex/Texan-midwest dishes, but not exclusively)
She Simmers (Thai food, mostly, but also other fun things)
Just HungryandJust Bento (Mostly Japanese recipes, but not exclusively)
When I’m bored I go to Tastespotting and click on foods that look delicious; it’s a great way to find new recipes that you’ve never heard of before.
Missed the edit window: if you’re a right click to new tab/window kind of a person, be forewarned: She Simmers is right-click disabled. I once spent a day alternately reading all her archives and trying to figure out how I was going to afford a new mouse.
I know the first two well 
I’ll check out the others tonight/tomorrow.
Right click disabled, what is this, fascism!?
You didn’t ask me, but I think two rinds would make the broth too salty. Save the other one and spread the goodness.
When I have rinds and am making minestrone, I just chop them into 2" pieces or so, throw them in as soon as the soup is assembled, and leave them in as tasty treats for whomever gets a piece in their bowl (no fair intentionally picking through the pot to get them!). After simmering, the rinds soften and get deliciously chewy and tasty. The rule about not taking them all has to get vigorously enforced, trust me.
Since I add a lot of beans (cooked from dried), and don’t use salty chicken stock, I have to add a lot of salt to the soup, so never worry about too much salt from rinds.
The rinds are in addition to a little grated cheese and olive oil on top of the soup.
Whoops! I didn’t intentionally not ask you; I was trying to mention everyone who helped me :p. I’ll stick to just one.