Cook the chorizo in the oil in a large pot over medium heat, stirring occasionally, about 5 minutes. Using a slotted spoon, transfer the chorizo to a plate lined with paper towel.
Add the carrots, onion, garlic, tomato and scallions to the pot, season with salt and pepper. Cook stirring occasionally about 12 minutes. Stir in the cumin and cook 1 more minute.
Add the lentils and water, bring to a boil. Then reduce the heat to medium low, cover and cook until the lentils become tender but not mushy about 45 minutes.
Add chorizo and potatoes, cook for 15 to 20 minutes until the potatoes are fully cooked and fork tender, thin with water if necessary. Ladle into soup bowls and top with cream if using and serve immediately.
Cilantro cream
If you are adding cream to the lentil soup. Mix all the ingredients for the cream and set aside. Drizzle the soup with it before serving.
Notes
*To store this lentil soup, place leftover soup in an airtight container in the refrigerator for up to 3 days. If you want to freeze it, store soup in an container in the freezer for up to 1 month. Be sure the container is freezer friendly. When you are ready to use it thaw overnight in the fridge or before reheating.*To reheat the soup, place the soup in a pot on the stove over medium-low heat until warm or reheat it the microwave.