Heat the oil in a large soup pot over medium-low heat. Add the onion and garlic and sauté, stirring occasionally, until the onion is golden, 8 to 10 minutes.

Add the broth (or water and bouillon cubes), mushrooms, cabbage, cumin, and salt-free seasoning. Bring to a rapid simmer over medium-high heat, then lower the heat, cover, and simmer gently for 15 minutes, until the cabbage is tender.

Meanwhile, set aside half of the chickpeas. Place the rest in a food processor or blender with the tahini and about ½ cup water, adding a little more water as needed to keep it moving. Process until completely smooth, then stir the puree into the soup.

Stir in the reserved whole chickpeas and return to a simmer. Cover and simmer very gently for 10 minutes, stirring occasionally so the soup doesn't stick to the bottom of the pot.

Stir in the parsley, scallions, dill, and lemon juice. Add water as needed, a little at a time, for a medium-thick consistency.

Season with salt and pepper and simmer for 5 minutes longer. Serve at once, or let the soup stand off the heat for an hour or two to let the flavors meld, then heat through gently before serving.