Start by heating olive oil and butter in a large pot over medium heat.
Once the oil is hot, add your chopped onions and cook them until they’re golden brown and soft, about 10-15 minutes.
Add the garlic and cook for another 1-2 minutes, until fragrant.
Next, add the peeled and diced potatoes into the pot. Stir them around for a minute so they’re coated with onions and garlic. Then add red chili flakes, oregano, bay leaf and pour in vegetable broth, and bring the soup to a boil.
Once it starts boiling, reduce the heat to a simmer and cook for about 20-25 minutes, or until the potatoes are tender and mushy.
Remove the bay leaf and transfer the mixture to a blender to puree it for a velvety smooth soup.
Season the soup with salt and pepper, pour the soup into the serving bowls, and add a dollop of olive on top.
Your potato and onion soup is ready to serve hot with a slice of garlic bread on the side.