If there is anything I can do to avoid food waste, I’ll do it. While I am not as extreme as my German grandmother who saved every single scrap, her ways definitely shaped me (which you can read about in more detail here).
Milk that nears expiration is turned into rice pudding, dry bread into breadcrumbs or it’s used for baking bread (the recipes of German home bread-baking guru Lutz Geissler, whom I interviewed for my German food blog here, often call for ground up dried sourdough bread). The carcass from a chicken or the Thanksgiving turkey becomes broth, egg whites are frozen to make meringue or angel food cake for trifle. I draw the line when anything is spoiled, or when saving a small amount of leftovers requires a whole bunch of good ingredients.
During the summer, my garden yields loads of vegetable scraps that are too good for composting yet still perfectly fine to make the best vegetable stock. I simply throw them into large containers in the freezer all summer long, and then make a big pot of stock.
After making vegetable stock this way for years (you can find my recipe here), I changed my formula last year and switched to making highly concentrated vegetable stock cubes simply because freezer space is so limited. A dozen quarts of vegetable stock take up valuable real estate that are better used for other produce from the garden.
Making vegetable stock cubes involves a few extra steps but it’s totally worth it. The inspiration for the stock came, like so often, from Deborah Madison’s Vegetarian Cooking for Everyone, which is the book I’d take to that famous island if I could only take one cookbook with me. In it she provides detailed lists of vegetables to include and to avoid in vegetable stocks, both summer stock and winter stock, and other ingredients to add depth to stocks, as well as tips for making stocks.
I admit, the muddy vegetable stock isn’t pretty nor photogenic. But the frozen cubes are extremely useful, and they take up almost no freezer space.
Vegetable Stock Cubes
Depending on the soup I am making, I dilute the stock cubes in different amounts of boiling water. For more delicately flavored and light colored soups such as cream of vegetable soups, I use 1 stock cube for 3 to 4 cups of water. For more robust soups like lentil or bean soups or minestrone, I use 1 cube for 1 to 2 cups of water. And I don’t add salt to the stock but you can if you like.
This year I used the following vegetables simply because I had them; next year, it might be a different mix depending on what I grow in my garden:
Swiss chard stalks, spinach stems, leek trimmings, parsley stems and leaves, ends of eggplant and zucchini, tomato skins (left over from making tomato sauce), peas and green beans including their shells, celery trimmings, lettuce.
I add the leafy and chunky vegetables at different stages, and since I collected them all together, I have to sort them when making the stock. If you find that too tedious, just freeze them separately.
¼ cup (60 ml) olive oil
6 pounds (2.75 kg) mixed vegetable scraps, coarsely chopped
2 large onions, chopped
1 bunch fresh thyme
3 bay leaves
1. Heat oil in a large skillet and fry onion until it starts to turn a deep yellow, stirring often.
2. Add all the chunky vegetables and fry until they start to brown. Add thyme and bay leaves.
3. Add the remaining vegetables and cover. Cook until the vegetables are soft and mushy, about 15 to 30 minutes depending on the amount of chunky vegetables. Stir every so often to make sure they don’t stick to the bottom of the pot and burn.
4. Let cool slightly, then puree (I use a stick blender). Pass through a food mill or a strainer.
5. Transfer the strained mixture to a large heavy pot (a Dutch oven is ideal) and discard the peels, seeds etc. that are left in your food mill. Bring the strained mixture to a boil, then reduce the heat and cook over very low heat until it is so thick that a cooking spoon leaves a trace. Stir often to avoid scorching, especially towards the end.
6. Let cool then fill in ice cube trays and freeze until solid.
7. Place the frozen cubes in a jar or container with a tight-fitting lid and store in the freezer.
Makes about 36 vegetable stock cubes
Photos by Ted Rosen
Green Card Gardener 
Are the outer dried onions skins used in stock? When I lived in town and had a freezer in the kitchen, we froze the onion skins along with everything else. I sort of thought that was an important part to vegetable stock. I really don’t know what it did, because it was just sort of always in there.
Tony, I am not using dry outer skins of the onions, I always have so many other onion-y scraps but I guess if they are organic you could.
We do not use them for lack of vegetation. They supposedly add a distinct flavor that the fresher parts of the onions lack.
Nadia, thanks for another very practical post. I smiled from ear to ear when I saw that WEAR-EVER No 8 STRAINER SIEVE COLANDER in your photo. [I’ve always call it a food mill, which it is, of course.] Those jobbies from the 1920’s and 1930’s are the absolute best for so many purposes. In making a simple tomato purée in the style of Marcella Hazan, I’ve always used it. I have a fancy Italian food mill with the three replaceable discs and it simply does not compare with the efficiency (the force you can bring to bear on the material inside with that massive wooden pestle) and ease of clean up of my several Wear-Ever # 8’s. Gotten for a song on eBay, I’ve always wondered why more cooks don’t use them.
Gestur, Agree, that strainer is terrific. I too have a modern food mill with several disks but ever since I bought the vintage Wear-Ever, it’s been in the cabinet untouched.
Nadia, I love Deborah Madison’s book and after reading this post I’m definitely motivated to try making these cubes (which will come in handy for the upcoming cold “soup days” in our mostly vegan household)!