Suppengrün is the German version of the aromatic vegetables that form the base of many stews and braises (Mirepoix in French, Soffritto in Italian), which translates to "Soup Greens." This variation uses leek or onion, celery root (a.k.a. celeriac), and carrot. There are two ways to use suppengrün: to make a liquid base for a soup, boil large chunks of each for a few hours, and then discard the spent vegetables. Add some parsley and salt and you have a simple veggie stock. Or, if you're preparing a meat dish or a braise, prep first: peel the celeriac, use only the white and light-green parts of the leek, and discard carrot tops. Chop all three veggies into a small, 1/2" dice, and sauté in a fat (oil or butter), until aromatic.
Split Pea Soup is an easy, make-ahead dish that reheats well and is perfect for Fall.