1/4 cup extra-virgin olive oil
12 ounces Spanish-style chorizo sausage, cut into 1/2-inch pieces
1 onion, chopped fine
4 garlic cloves, minced
Salt and Pepper
1/4 tsp red pepper flakes
2 pounds Yukon Gold potatoes, peeled and cut into 3/4-inch pieces
4 cups chicken broth
4 cups water
1 pound collard greens (or kale), stemmed and cut into 1-inch pieces
2 tsp white wine vinegar
1. Heat 1 tablespoon oil in a Dutch oven over medium-high heat until shimmering. Add chorizo and cook, stirring occasionally, until lightly browned, 4-5 minutes. Transfer chorizo to bowl and set aside. Reduce heat to medium and add onion, garlic, 1 1/4 tsp salt, and pepper flakes and season with pepper to taste. Cook, stirring frequently, until onion is translucent, 2 to 3 minutes. Add potatoes, broth, and water; increase heat to high and bring to boil. Reduce heat to medium-low and simmer, uncovered, until potatoes are just tender, 8 to 10 minutes.
2. Transfer 3/4 cup solids and 3/4 cup broth to blender jar. Add collard greens to pot and simmer for 10 minutes. Stir in chorizo and continue to simmer until greens are tender, 8 to 10 minutes longer.
3. Add remaining 3 tablespoons oil to soup in blender and process until very smooth and homogeneous, about 1 minute. Remove pot from heat and stir pureed soup mixture and vinegar into soup. Season with salt and pepper to taste, and serve.
Recipe from Cook's Illustrated November and December 2013