Winklers Zum Posthorn
Zum Posthorn is a charming neighborhood restaurant not too far from Vienna's city center in District 3, run by the Winkler family (it's nice to see that Winkler junior, in his late twenties, is also involved). Some of the weathered furnishings go back to 1870, but my favorite design piece is the giant wooden cupboard behind the bar where they store wine and beer. At all times, especially in the evenings, the small tables are filled to the brim by local regulars that may include the Austrian President, Alexander Van der Bellen, so be sure to book in advance (by phone).
Start with the flavor-rich beef broth in which proudly sit two plump liver dumplings and crunchy bits of root veggies, then progress to more dumplings, these ones studded with spinach and parmesan and moistened with melted butter. The schnitzel and the roasted veal kidney with mashed potatoes are also excellent. With mains ranging €11-18, prices are very reasonable for Vienna. Closed on Saturday and Sunday!