Crema de Cepa de Apio [Recipe + Video] Arracacha Soup

• 2 tablespoon olive oil
• 1 large red onion chopped
• 1 teaspoon cumin powder
• 1 bay leaf
• 3 celery stalk chopped
• 2 carrot peeled and sliced
• 1 cepa de apio (about 2 lb [0.85 kg]), peeled and chopped
• 4 potatoes peeled and cubed
• 1½ quart vegetable broth [1.5 lt] or homemade vegetable broth recipe
• 1½ teaspoon salt (or more, to taste)
• ½ teaspoon pepper (or more, to taste) (freshly-cracked, or ground)

For garnishing

• 4 tablespoon sour cream (optional)
• 4 tablespoon olive oil (optional)
• parsley (optional)
• ½ teaspoon pepper (freshly-cracked, or ground) (optional)