Heat a heavy soup pot. Remove the casing from the sausage, crumble into the pot, and cook until just about done and the fat is rendered. Add the chopped leeks, and cook, stirring until the leeks start to soften, about 5 minutes. Add the Puttanesca Pizza & Pasta Sauce. Rinse out the jar with water, and add the 2 cups water. Bring to a simmer and cook, covered, for 15 minutes. Stir in the spinach and cook until wilted, about 5 minutes. Season to taste with sea salt and fresh pepper. Ladle into soup bowls and serve. Makes six servings.