Place the vegetables in a large bowl of cool water as you finish preparing each, in this order: Keeping the stem end intact, cut the cabbage into four wedges. Trim the zucchini ends, and cut in half lengthwise. Cut the half pumpkin into four wedges. Trim tops and bottoms of carrot and parsnip, then cut in half crosswise, then in half lengthwise. Cut the turnip into 4 wedges. Set aside the vegetables in their bowl of cool water.
Heat the olive oil in a large pot over medium heat. Add the chopped onions and cook until soft — 5 minutes. Add the chopped tomatoes and continue cooking for 5 minutes until they have broken down. Add the spices (turmeric, ginger, paprika, pepper) and salt; cook 1 minute. Add the tightly tied bouquet of parsley and 1/4 cup of the vegetable broth; cook for 10-15 minutes over medium-low heat, stirring frequently to keep it from sticking. You want to have the flavors blend well.
Add the tomato paste to the onion/tomato mixture and stir well. Add the remaining broth and bring to a gentle boil.
Add the hardest vegetables first: carrots and turnips. Stir to cover the vegetables, bring to a brisk simmer, and cover the pot. After 5 minutes, add the parsnips, and cover.
After 5 minutes more, add the pumpkin; stir gently, cover.
After 10 minutes, add the zucchini and cabbage, and cover.
After another 10 minutes, add the chickpeas, cover and cook until heated through — about 1 minute
Check that all vegetables are tender and broth has thickened a bit. Remove and discard the parsley. Keep the vegetables warm while you make the couscous.