Caldo Verde
Bright in color and hearty of flavor, Portuguese “green soup” is a surefire wintertime hit.
Caldo verde, the “green soup” that is one of Portugal’s best-known and -loved dishes, is a great way to start the year. Though the ingredient list is short -- potatoes, greens, and a little sausage in an onion- and garlic-infused broth -- the combination strikes an almost magical balance of complementary qualities: It’s somehow both hearty and light. A preponderance of very thinly sliced greens, usually kale or collards, gives the soup an emerald luminosity that seems to promise good health for both the body and spirit.
In his recent book The New Portuguese Table, David Leite describes the custom of including just a single slice of sausage for each serving -- though his recipes call for more. Like Leite, I serve a few slices per diner, yet the overall quantity of sausage remains modest at 1/2 pound for four to six servings. This keeps the spotlight on the real stars of the show, the potatoes and greens.
Caldo Verde (Portuguese Green Soup)
Makes about 2½ quarts
1/4 cup extra-virgin olive oil
1/2 pound chourico, linguica, or dry-cured chorizo sausage, sliced 1/4 inch thick
2 medium onions, chopped
Salt
3 cloves garlic, minced
2 quarts homemade or packaged low-sodium chicken broth, or water
2 pounds Yukon Gold or red potatoes (about 4 medium), peeled and sliced about 3/8 inch thick
1 bunch (about ¾ pound) kale or collard greens
Pepper
2 teaspoons cider vinegar, or more to taste
In a large Dutch oven over medium heat, heat the olive oil until it ripples. Add the sausage and cook, stirring frequently, until it browns lightly, about 4 minutes. With a slotted spoon, remove the sausage to a paper towel-lined plate to drain, and set aside. Pour all but about 1 tablespoon of the oil into a small bowl, and set aside.
Return the pot to medium heat, add the onions and a pinch of salt, and cook, stirring frequently, until onions are softened, about 5 minutes. Stir in the garlic and cook until fragrant, about 1 minute. Add the broth or water and potatoes, increase the heat to high, and bring to a strong simmer. Cover and cook vigorously until the potatoes are soft around the edges but still firm in the center, about 7 minutes. (If you prefer a thicker broth, mash about half of the potatoes against the side of the pot.) Adjust the heat to medium-low and simmer for 2 minutes longer.
Meanwhile, cut out and discard the tough center stems of the kale or collard leaves. Following the directions in Kitchen Aide, chiffonade the greens (you should have about 8 cups). Add the greens and cooked sausage, stir to mix, and simmer just until the greens are tender and bright green, about 4½ minutes. Add 1½ teaspoons salt, pepper to taste, and 2 teaspoons of vinegar, and stir to mix. Taste the soup and adjust the seasoning with salt, pepper, or vinegar, if necessary, and serve at once, drizzling each portion with some of the reserved oil.
Variations Azorean-style Caldo Verde with Beans, Adapted from David Leite’s The New Portuguese Table This spicy version adds beans to the pot.
Follow the recipe for Caldo Verde, adding 1/2 teaspoon crushed red pepper flakes along with the garlic, decreasing the quantity of potatoes to 1-1/2 pounds, and adding 1 19-ounce can red kidney beans, well rinsed, when you stir in the greens and cooked sausage.
Caldo Verde with Mustard Greens and Sweet Italian Sausage
The sweet sausage and leeks provide nice counterpoints to sharp mustard greens.
Follow the recipe for Caldo Verde, making the following changes:
1) Substitute 1/2 pound of fresh, sweet Italian sausage for the chourico, linguica, or dry chorizo, and reduce the quantity of olive oil to 1-1/2 tablespoons. Heat the oil over medium heat until it shimmers, and cook the sausages, turning them occasionally, until browned all over, about 9 minutes. Remove the sausages and, when cool enough to handle, slice them into 1/2-inch rounds.
2) Substitute 2 medium leeks, white and light green parts only, cleaned well and chopped (about 4 cups) for the onions, and cook them for 3 minutes before adding the garlic.
3) Substitute mustard greens for the kale or collard greens.
4) Omit the vinegar and top each serving with a drizzle of extra-virgin olive oil.
Caldo Verde with Roasted Sweet Potatoes and Hot Italian Sausage
Use Tuscan kale (also called laciniato kale, dinosaur kale, black kale, or cavolo nero) in place of the collards or kale if you can find it. Likewise, spicy lamb merguez is wonderful in the soup, but it’s harder to find than hot Italian sausage.
Follow the recipe for Caldo Verde, making the following changes:
1) Substitute 1-1/2 pounds oven-roasted sweet potatoes for 3 of the 4 Yukon Gold or red potatoes. (To roast: Toss peeled 1½-inch sweet-potato chunks in salt, pepper, and 2½ tablespoons of the oil and roast at 450 degrees for 25 minutes.)
2) Substitute 1-1/2 pound of fresh, hot Italian sausage for the chourico, linguica, or dry chorizo. Heat the remaining 1-1/2 tablespoons of oil over medium heat until it shimmers, and cook the sausages, turning them occasionally, until browned all over, about 9 minutes. Remove the sausages and, when cool enough to handle, slice them into 1/2-inch rounds.
3) Boil the Yukon Gold or red potato in the broth or water mixture until very soft, about 13 minutes, and mash it against the side of the pot to thicken the soup.
4) Add the roasted sweet potatoes along with the greens and cooked sausage.
5) Top each serving with a drizzle of extra-virgin olive oil.
Send comments or suggestions to Adam Ried at cooking@globe.com. 
