Three Bean Minestrone Soup

olive oil

large onion (chopped small, about 2 cups)

beef stock or 8 cups water plus 3 tablespoons beef base

can tomato sauce

carrots (sliced 1/4" thick, about 3 cups worth)

stalks celery (trimmed and sliced 1/4" thick, about 2 cups worth)

can kidney beans

can navy beans or white beans

can black beans

dried oregano

dried thyme

kosher salt (adjust to taste (I added another 1/2 teaspoon, because my beef stock wasn't very salty at all))

freshly ground black pepper

cooked pasta (I used a brown rice penne pasta)

finely grated Parmesan or Pecorino Romano cheese

Optional: 1 pound Italian or hot sausage