If you want a single restaurant to stand for the Paris bistro at its finest and most unreconstructed, Bistrot Paul Bert is it. Zinc bar, chalkboard menu, paper tablecloths, waiters in aprons, the same dishes for twenty years: steak frites, bone marrow, crème brûlée in a dish the size of a hubcap.
The €19 lunch menu — three courses — is extraordinary value for cooking of this quality. The wine list is long, fairly priced, and weighted toward the natural and biodynamic. Book ahead.