Combine cinnamon, cumin, ginger, cloves, nutmeg, turmeric, curry powder, and salt in a large bowl, reserve.
Melt butter in a large saucepan over medium heat. Cook the onion in the butter until soft and just beginning to brown, 5 to 10 minutes. Stir in the kale and reserved spice mixture. Cook for 2 minutes or until kale begins to wilt and spices are fragrant.
Pour the vegetable stock into the saucepan. Stir in the tomatoes, honey, carrots, kumara, potatoes, garbanzo beans, dried apricots and lentils. Bring to boil; reduce heat to low.
Simmer stew for 30 minutes or until the vegetables and lentils are cooked and tender. Season with black pepper to taste. If desired, combine optional cornfour and water; stir into stew. Simmer until stew has thickened, about 5 minutes.
If making ahead or freezing, prepare stew through Step 3. Simmer for 5 minutes over low heat; remove from heat and cool in the saucepan or in freezer-safe container. Transfer to the fridge (store for up to 3 days) or freezer. The vegetables store better if not fully-cooked prior to refrigeration or freezing. When ready to eat, (if frozen) thaw in refrigerator for 24 to 48 hours then pour stew into a pot, bring just to a boil and simmer until heated through.
Kumara is known in other parts of the world as a sweet potato.