White Bean & Italian Sausage Soup

3 tablespoons olive oil

3 tablespoons salted butter

1 large yellow onion, diced

1 large carrot, finely diced

4 tablespoons tomato paste

2 teaspoons salt

½ teaspoon ground cumin

½ teaspoon garlic powder

1 pound ground Italian sausage (or substitute ground beef or pork)

32 ounces chicken broth (p. 225) or bone broth (p. 108)

2 (15-ounce) cans white beans, drained and rinsed

1 bunch greens, roughly chopped (e.g. mustard greens, broccoli rabe, chard, or collard greens)

Shaved Parmesan, optional

Fresh herbs, optional

Lemon juice, optional