Kale Minestrone with Pistou

Tie oregano, rosemary, and bay leaves together with kitchen twine. Heat oil in a large heavy pot over medium. Add pancetta, if using, and cook, stirring often, until browned around the edges, about 5 minutes. Add onion, leek, carrots, celery, garlic, and red pepper flakes; season with salt. Cook, stirring often, until onion is translucent and carrots are tender, 10 –12 minutes. Add tomato paste and cook, stirring to coat, until slightly darkened, about 3 minutes. Add tomatoes, crushing with your hands as you go, then herb bundle, Parmesan rind, if using, and 6 cups water or reserved bean cooking liquid, or a combination. Season with salt and pepper and bring to a boil. Add potatoes, reduce heat, and simmer until potatoes are tender and flavors have melded, 20 –25 minutes. Add kale and beans; cook until kale is tender, about 5 minutes. Discard Parmesan rind and herb bundle. Do ahead: Soup can be made 2 days ahead (or 2 months if frozen). Let cool; transfer to airtight containers and chill.