Place large pot over medium-high and add oil.
Add prosciutto and hot pepper flakes, if using, Add carrots, celery, and onions and sauté for about 5 minutes, or until fragrant. Then add garlic and cook for about 1 minute.
Add the tomatoes and stir.
Add the water and lentils.
Add the oregano.
Bring to a boil, then reduce heat to medium-low, cover, and simmer 40 minutes, stirring occasionally. The lentils should be soft but still hold their shape.
Add parsley.
Add salt and pepper.
Add spinach or kale. Add pasta, if using.
Remove cheese rind, if using. (It can be chopped up and served with soup.) Adjust seasonings. Serve hot in bowls.
Drizzle of Nardini’s Private Label Extra Virgin Olive Oil. Serve with crostini.