2 cups green lentils or small Italian brown lentils

1/4 cup extra virgin olive oil, plus more for drizzling

4 to 6 large garlic cloves, lightly crushed

1 large celery rib, finely diced

1 medium yellow onion, finely diced

1 small fennel bulb, finely diced

1 fresh or dried peperoncino or pinch of crushed red pepper

3 thyme sprigs

1 bay leaf (fresh or dried)

1 teaspoon sea salt (or to taste)

1 medium yellow potato, peeled and cut into 1/2-inch cubes

4 cups vegetable broth (or chicken broth)

4 cups water

2 cups cubed bread (1/2 inch cubes, optional for croutons)

2 tablespoons extra virgin olive oil (for croutons)

Kosher salt (for croutons)

Black pepper (for croutons)