Heat avocado oil or other neutral cooking oil in a heavy-bottomed pot over medium-high heat. Add the chopped onions and sauté until the onions are soft and translucent, about 5 minutes. Add the minced garlic, cumin powder, chili powder, dried oregano and continue to cook until the garlic is fragrant, about 2 minutes.
Add the diced carrots, butternut squash, and canned tomatoes, crushing the tomatoes with a ladle or spoon if you're using whole tomatoes. Add barely enough stock or water to cover the vegetables. Bring to a boil, then turn down the heat and simmer for 20 minutes, or until the butternut squash is tender. Exact cooking times will depend on the size of your vegetables.
Add zucchini, black beans, salt, and pepper. Add more stock or water if necessary. Simmer until the zucchini is tender, about 10 minutes.
Taste the chili and adjust with additional salt and pepper as needed.
Serve chili in bowls, with shredded Jack cheese and/or crumbled cotija cheese, crema or other thick cream, chopped avocado, diced red onions, chopped scallions, sliced jalapeño, fresh cilantro leaves, fresh lime wedges, Fritos, bottled hot sauce on the side. Everyone can dress their chili bowls as they like.
Keep leftover chili in tightly sealed container in refrigerator for up to two days. Leftovers taste great on their own, but also work well as a "sauce" for pasta, on nachos, or as a vegetarian taco filling if you heat the chili in a pot and cook off some of the liquid.