Heat the olive oil in a large pot set over medium heat. Add the onion and garlic and cook for 6 minutes, until the onions become translucent. Add the cumin and continue to cook for another minute.

Add the lentils, stock, salt and pepper, and simmer for 30 minutes, or until the lentils have broken down. Add water if the soup needs thinning.

Stir in the lemon juice, taste, and reseason if necessary.

Ladle into soup bowls and drizzle with olive oil to serve.

Tip: There are many varieties of lentils: red, green, yellow, and black. Although green is the easiest to find, any variety works well in this soup.

Make ahead: This soup can be made up to 2 days ahead and kept covered in the refrigerator.