In a large pot, sauté the onion and garlic in the olive oil, for a few minutes, until the onion is translucent.Then stir in the celery and season it with the salt.Let this mixture cook for a couple of minutes, then stir in the mushrooms.Let this cook for a few minutes more.Then stir in the thyme, rosemary, broth, and add the bay leaf.Add the lentils. Bring the mixture to a boil. Then reduce the heat to medium and cook uncovered for 20 – 25 minutes.Add the pepper.Stir in the kale strips and cook for a couple of minutes until the leaves have wilted.Serve.