Beans

Kombu (dried Japanese kelp seaweed), one 4-by-6-inch piece
Dried borlotti or cannellini beans, 1½ pounds
Smoky bacon (such as Benton's or Nueske's), 4 ounces (preferably in 1 piece rather than strips)
Extra-virgin olive oil, 2 tablespoons plus 1 teaspoon, plus extra for serving
Medium white onion, ½ (finely chopped)
Celery, 1 stalk (finely chopped)
Fennel fronds and stalks, from 1 bulb (finely chopped)
Fresh sage leaves, 8 (finely chopped)
Dried bay leaves, 2
Fresh rosemary, 1 medium sprig (needles removed and finely chopped)
Garlic clove, 1 (smashed with the side of a chef's knife)
Dried red pepper flakes, 1 pinch
Freshly ground black pepper, 1 pinch
Parmigiano-Reggiano cheese rind, 1
Flaky salt, for serving
Grated Parmigiano-Reggiano cheese, for serving

EQUIPMENT

Cutting board
Chef’s knife
Measuring cups and spoons
Mixing bowls
Kitchen scissors
Plastic wrap
Colander
Soup pot
Wooden spoon