Heat oil in large pot over medium heat. Add onion, garlic and thyme. Sauté until onion is golden about 8 minutes. Add beans, bean liquid, 4 cups broth, tomatoes with jiuce, cumin and hot pepper sauce. Bring to a boil.
Reduce heat to medium-low and simmer until flavors blend and soup thickens slightly, stirring occasionally, about 20 minutes.
Allow to cool slightly.

Working in 2 batches, puree 2 1/2 cups soup in a blender until smooth. Mix puree back into soup pot, bring to a simmer.
Season to taste with salt and pepper. Serve with a dollop of sour cream or yogurt(optional).

Note: Can be made 1 day ahead. Cool slightly, refigerate uncovered until cold, then cover and keep refigerated until ready to serve. To serve, bring soup to simmer, thinning with more broth if needed.