Melt the cooking fat in a medium stockpot over medium heat. Add the diced onions and salt, stir well to coat, and let cook stirring every so often, until the onions have softened and are beginning to caramelize - approximately 10 minutes. Add the thyme and oregano, and garlic, stir well to coat, cook for 2 minutes.
Add the canned tomatoes, tomato paste, 3 cups / 750ml vegetable broth, and butter beans. Bring to a boil, reduce to simmer, and cook for 5-10 minutes. Carefully transfer the soup to a blender (or use an immersion blender). Add the soaked and drained cashews, nutritional yeast, balsamic, and cracked black pepper. Blend on high until completely smooth (this may take a few minutes, but the creamy consistency is the beauty of this soup, keep blending!). Add more vegetable broth or water, as needed.
Serve with toasted sourdough, a drizzle of olive oil. I added fried mustard seeds to my bowl, yum. Say thank you and enjoy.