This particular recipe is my own creation, based on what was in my kitchen, but is entirely inspired by history. Several parts of history, in fact.
The first is reducing food waste. Historical peoples did not throw out potatoes just because they were starting to sprout, or lettuce because it was a bit wilted, and neither should you. Putting lettuce in soup is also extraordinarily historic, and a practice that should be revived.
Another is that this recipe is based on one of my favorites, "Green Onion Soup," from Rae Katherine Eighmey's Hearts & Homes: How Creative Cooks Fed the Soul and Spirit of America's Heartland, 1895-1939 (2002). Eighmey read hundreds of agricultural magazines and gleaned recipes and wisdom from the farm home sections. Found in the December 26, 1924 issue of Wallace's Farmer, Green Onion Soup is a unique recipe. A combination of simply green onions and potatoes, the soup is cooked in a small amount of water, and then partially mashed right in the pot without draining. Cream and milk are added to thin the soup and add richness. The soup is comforting and nourishing and retains all of the vitamins and minerals that might otherwise be lost by draining away the cooking water.
Which brings me to the final inspiration - vitamin retention in the style of recipes from World War II. By cooking the vegetables in the water that becomes the broth, you lose far fewer nutrients and flavor. Plus, other aspects of the soup are also quite appropriate to WWII - it's meatless, in line with rationing, and makes good use of milk, a favorite 1940s ingredient.
Creamy Kitchen Sink Soup Recipe
4 red potatoes
2 bunches green onions (scallions)
1 celery root
3 cloves garlic
1 head red lettuce
1-2 cups baby spinach
1/2 cup half and half
1 cup buttermilk
Scrub and dice the potatoes, cutting away any eyes or bad parts, but leave the skin on. Slice the green onions, white and green parts. Cut away the knobbly skin from the celery root, then cut into small dice. Mince the garlic, wash and chop the whole head of lettuce. Add it all, with the spinach to a large stock pot and add water not quite to cover. Add at least 1 teaspoon salt (I used wild garlic flavored crystal salt languishing in a drawer) and bring to a boil. Reduce heat and simmer hard until all vegetables are very tender and potatoes fall apart when pierced with a fork. Do not drain. Using a potato masher or sauce whisk, mash vegetables in the pot until blended with the water, leaving some chunks.
Add a the half and half and buttermilk (or you could use part heavy cream, or leave out the buttermilk, or just use milk) then add milk to thin out the soup and to taste. Taste for salt and add more if necessary, along with pepper and whatever other herbs and spices you like. Serve nice and hot with buttered bread or toast.
The buttermilk does add a nice, distinctive tang. If you don't have any, add a dollop of sour cream, or some plain yogurt, or a splash of lemon juice.
You could make this vegan with plant-based milk and butter. For a different flavor, add whatever fresh herbs you have lying around - dill, parsley, basil, and cilantro would all be good here. Add vegetable broth and some lemon juice instead of milk for a bright, brothy soup instead of something creamy. Use sweet potatoes or squash and tomato broth with the greens. The possibilities are really endless.