There might be more excellent tacos per square block in Mexico City than anywhere else in the known universe. And while most of them are filled with delicious meats and fish, there are no better vegan tacos than those found at Por Siempre Vegana. The taco de milanesa, served with avocado, is incredible, and worth the almost constant wait for a table here during peak hours. This spot is affordable, and sticks to mostly one thing: 90% of the menu is tacos. Make sure to take advantage of the unlimited free toppings, too.