Preheat a soup pot over medium heat.
Add the oil, if using.
Saute the onion for 2 to 3 minutes or until barely translucent.
Add the celery and carrot, and cook for another 2 to 3 minutes.
Add the garlic, thyme, parsley, oregano, red pepper, black pepper, and salt. Stirring frequently, cook for about 1 minute.
Sprinkle flour into the pot, and stir to distribute.
Add the milk, and whisk to dissolve the flour.
Bring to a simmer, and cook until thickened, about 3 minutes.
Add the water, broth and potatoes/pasta, if using.
Simmer about 5 minutes.
Add beans and kale.
Simmer for about 5 more minutes, or until potatoes/pasta are soft.
Taste and adjust seasonings as desired.
The soup will continue to thicken as it rests.