Turn oven to 375.
Chop the zucchini into 1/2" pieces, slice the tomatillos in half (quart if large), the onions into sections, and the bell pepper into strips. All should be roughly the same size.
Toss veggies in a big bowl with a splash of oil and all the spices. Scatter across one or two cookie sheets (they should have some room between them so they roast instead of steam.)
Bake for 25 minutes, toss and rotate pans, and then put back in for an additional 10-15.
Add all items to Vitamix, blender or food processor, with enough water or stock to make into soup (around 2-3 cups most likely.)
Reheat in a pot, and taste to adjust seasoning. Tomatillos are mildly spicy, so if it's too much heat, temper it with honey or lemon juice.