I started making my own veggie broth just so I would have some type of nutrient-rich broth to use to puree foods for my son. I was surprised at how simple it was to make and I've learned to use it for so many different things. Here are the steps I take to keep this on hand for making soups, beans, and lots of other dishes.
I keep a zipper freezer bag ready to go all the time. At any given time, you'll find a freezer bag partially filled with veggie pieces. Once it gets full, I make my broth. What do I put in it? Almost anything you cut off a vegetable can go in the bag. Pepper tops, onion ends, broccoli stalks, cauliflower leaves, tops of carrots, and tons of other bits and pieces. Once the bag gets full I am ready to make the broth.
Making the Broth
I use an instant pot to make my veggie broth. But before I had my instant pot I cooked it on super low on the stove for several hours. Either way works fine. Simply put the frozen (or fresh) veggie pieces in the pot and cover with water. Let it simmer for three or four hours on the stove. Or, if you are using the instant pot, set it to cook for 11 minutes. Once it is done, you can either let the steam off manually or let it go down naturally.
After the broth is done, use a strainer to separate the now cooked veggies from the broth. I suggest putting the veggies in the compost pile if you have one. Then store the broth in a glass jar for up to a week in the fridge. You can also freeze it and use it in beans, rice, or soups as needed.