2 large (about 13 ounces) cooked chorizo sausages, sliced (optional)1-1 ½ cups French green lentils, picked over and rinsed (see note)1 tablespoon olive oil½ large onion, chopped2 medium carrots, peeled and diced2 cloves garlic, minced2 (14.5-ounce, no salt added) cans diced tomatoes with their juice8 small red waxy potatoes, scrubbed, quartered and soaked in 3 cups water1 teaspoon salt1 teaspoon freshly ground black pepper1 teaspoon paprika½ teaspoon cumin seed, lightly crushed½ teaspoon ground coriander3 cups chopped greens, such as kale or Swiss chard (tough stems discarded)For the garnishesGood-quality olive oilParsley, choppedGrated hard cheeseIf using the chorizo, brown the slices in a heavy-bottomed pan over medium-high heat. Drain on a plate lined with paper towels. Set aside.Place lentils in a large, heavy-bottomed soup pot. (Use 1 cup lentils if adding chorizo, or 1

½ cups lentils for a vegan soup.) Add water to cover by about 2 inches. Bring to a boil, then lower heat to a simmer. Cook lentils until tender, at least 30 minutes. (If necessary, add water while cooking.) Drain, then transfer lentils to a bowl and set aside.Return the pot to the stove over medium-high heat. Add olive oil. Once the oil is hot, add onion and carrots and sauté, stirring occasionally, until onion is translucent. Add garlic and stir for 30 seconds. Add diced tomatoes with their juice and potatoes with their soaking water.Bring the soup to a boil, then reduce heat. Add chorizo slices, if using. Let simmer, stirring occasionally, until potatoes are just tender, about 12 minutes.Stir together salt, freshly ground black pepper, paprika, cumin seed and coriander in a small bowl. Set aside.One the potatoes are cooked, stir in the lentils and chopped greens. Add spice mixture to taste. Continue to cook, stirring occasionally, just until greens are cooked. Add more spices as necessary.Divide the soup among bowls and serve it with desired garnishes: a drizzle of olive oil, a sprinkle of parsley or shavings of hard cheese all work well.Note: Don't substitute brown or red lentils because they don't hold their shape as well after cooking.Before cooking with any lentils, pick them over carefully and discard small rocks and shriveled lentils.