Cut tomatoes into large wedges and place into food processor or blender. Discard any hard parts.
Add the bread, garlic, red pepper, cumin, and saffron. Process until smooth. With the processor running, add vegan sour cream or yogurt, and sherry wine vinegar. It should be similar to the consistency of yogurt. Season with salt (optional) and pepper. Add more vinegar (don’t overdo this) and cumin if needed. Process the soup until foamy. Pour into 2 large soup bowls, or several smaller ones, and garnish as you like with avocado, sliced spring onion, or cilantro, and perhaps a spoonful of vegan sour cream. Serve chilled or at room temperature. Some like this just barely hot.