As one cooks more from whole food ingredients the vegetable trimmings pile up. The vegetable broth recipes where you put in perfectly good vegetables and then throw them out later have seemed wasteful to me, so making broth out of the onion skins and peels of the vegetables seemed like a fun experiment to try. And you’re not really supposed to put onion or garlic skins in the vermicomposting, so this is a way I could get some more use out of them.
https://www.garlicandzest.com/scraps-vegetable-broth/
Here is a tutorial for how to make vegetable broth from scraps. The particular vegetables and spices used is flexible.
Some places recommend not to add brassica veggies like (cabbage or broccoli) because it can tend to make the the broth bitter. And be warned that if you put any red beets in there it will turn your broth red. I usually just toss whatever veggies in there and it’s ended up okay. The stems of fresh herbs are also nice to use. Depending on what I have on hand I’ll add some whole spices, black peppercorns at the very least. I don’t add salt to the broth as I am making it, I usually wait to add it until I am cooking whatever recipe the broth ends up being in.
I keep a large ziplock plastic bag in my freezer and toss in the vegetable scraps as they are accumulated. When either the plastic bag is full or I’ve run out of broth I’ll make another batch on the weekend. I often make it while I am cooking something else because all you need to do is keep half an eye on a simmering pot for half an hour.
After I’ve let the broth cool and strained out the solids, I cool the broth completely. Then for easy access later I measure out 1 cup (or whatever quantity unit you’d like) portions into old plastic containers (like what yogurt or hummus had come in) and also fill an ice cube tray. I put the lids on the containers and stack them in the freezer until frozen solidly. Then I set them out on the counter for a bit until they’ve melted just the slightest bit until I can slide them out of the container and put into another large ziplock bag. (If you are too impatient to get them out this can cause the still-frozen plastic containers to crack, which is why I use resused containers. Hey, at least I get a few extra uses out of them before they go in the recycling bin.) That way when I have a recipe that calls for a cup or two of vegetable broth I can easily get out that amount from the freezer. And I also have the ice cube amount for when I just need a dash of broth.
You can match the flavor of your broth to your taste. It is infinitely cheaper (you’re making out of what would have otherwise been garbage) than storebought packaged broth or bullion cubes. It also doesn’t have any added salt if you don’t want and no preservatives (aside from the freezer).