How to Make It
Place a medium Dutch oven in oven. Preheat oven to 400°F. Toss together bell peppers, carrots, onion, squash, garlic, oil, miso, and 1 teaspoon salt in a medium bowl until vegetables are coated in miso mixture.
Add vegetable mixture to hot Dutch oven. Return to oven, and roast in preheated oven, uncovered, until vegetables are tender, about 45 minutes, stirring every 15 minutes and scraping to loosen any browned bits along sides of Dutch oven.
While vegetables roast, stir together canned tomatoes, soy sauce, thyme, paprika, cumin, pepper, 3 cups water, and remaining 1/2 teaspoon salt in same medium bowl. Remove vegetable mixture from oven. Pour tomato mixture over vegetables, and stir to combine (vegetables should be covered in tomato mixture). Return pan to oven, and cook, uncovered, stirring occasionally, until flavors are concentrated and vegetable mixture is very tender, 1 hour to 1 hour and 15 minutes (add up to 2 cups water as needed throughout cook time so vegetables stay just covered in liquid).
Transfer half of the vegetable mixture to a blender, and blend on medium speed to a coarse puree, 3 to 5 seconds; return to pan. Alternatively, use an immersion blender to blend soup in Dutch oven to desired consistency. Adjust the consistency with additional water, as desired. Season with salt and pepper to taste. Serve with a lemon wedges and bread for dunking.