When I made this, I tasted it before adding the optional ingredients and was ready to stop there–it was simple and delicious. But I couldn’t resist trying to make it a little creamier and richer, so I added the nutritional yeast and tahini (plus turmeric for color). I’ll leave it up to you to decide which way you like it best.
Heat a large non-stick or enamel-coated pot over medium-high heat. Add the onion, reduce the heat to medium, and cook, covered but stirring every minute or so, until it begins to brown, about 5 minutes (add a little water if it tends to stick). Add the garlic and hot pepper and cook for another minute.
Add all remaining ingredients except the optional ones. Cover and cook until the potatoes are completely tender (they will mash if lightly pressed with a spoon), about 25-40 minutes.
Remove half of the soup and put it into a blender* and puree at high speed until completely smooth. (Be careful–hot liquids can erupt from your blender; I always remove the center cup from the lid and cover the opening with a kitchen towel.) Once it’s blended, pour the soup into another pot. Add the remaining soup to the blender, along with any optional ingredients you choose to use, and blend well. Add to the other half of the soup, and simmer for about 5 minutes. Ladle into bowls, garnish with slices of red bell pepper, and serve.
*I like this soup blended smoother than my hand blender can get it.Nutrition Information is for soup without optional ingredients. With optional ingredients, each serving contains 161 Calories (kcal); 3g Total Fat; (14% calories from fat); 7g Protein; 30g Carbohydrate; 0mg Cholesterol; 34mg Sodium; 7g Fiber; 3mcg B-12.