When you're at the farmers' market, look for Red Russian kale, an heirloom variety that, despite the name, is purple and gray-green. Its tender texture and mild flavor go well in this lightly spicy soup.
8 ounces Spanish chorizo, thinly sliced crosswise
1 tablespoon olive oil
1 large onion, chopped
2 large garlic cloves, minced
1/2 teaspoon red chile flakes
1/2 teaspoon pepper
7 cups reduced-sodium chicken broth
3/4 pound russet potato, peeled and chopped
12 ounces Red Russian or other kale, stems removed and leaves cut into slender ribbons
Kosher salt (optional)
How to Make It
Cook chorizo in oil in a pot over medium-high heat, stirring often, until browned, about 5 minutes. Transfer chorizo to a paper towel with a slotted spoon.
Add onion to fat in pot and sauté until softened, 3 to 5 minutes. Stir in garlic, chile flakes, and pepper; cook about 1 minute. Add broth and potato; cover and bring to a boil. Reduce heat and simmer until potato is tender, about 5 minutes.
Stir in kale and chorizo; cover and bring to a boil. Reduce heat; simmer until kale is tender, 3 to 5 minutes. Season with salt.