Potato Leek Soup with Sizzling Herb Chili Oil

1 In a large pot over medium heat, melt butter and add a drizzle of oil. Add the onion and leek and cook for 5–7 minutes, stirring occasionally, until softened but not browned. Add the garlic and cook for 30 seconds, just until fragrant.
2 Add the potatoes, white kidney beans, chicken broth and water. Season generously with salt and pepper. Bring to a boil, then reduce to a simmer and cook for 20–25 minutes, or until the potatoes are fork-tender. Stir in the heavy cream and lemon juice. Taste and adjust seasoning as needed. 
3 Using an immersion blender or a blender, blend the soup until smooth and creamy. If using a blender, add back into the pot. Keep warm over low heat.
4 Heat the oil in a small saucepan over medium heat until very hot, but not smoking (the oil should be shimmering). Add the basil, parsley, green onions, grated garlic, chili flakes, salt, and pepper to a heatproof bowl. Carefully pour the hot oil over the herbs, it should sizzle immediately. Stir gently and set aside.
5 Ladle the soup into bowls. Top with a dollop of sour cream, spoon over the sizzling herb chili oil, and finish with cracked black pepper. Serve with toasted sourdough on the side and enjoy!