Not all of Puerto Madero has convenient metro stops, but all restaurants are, at most, a 20-minute walk from a metro station.
There are no convenient metro stops in this neighborhood.
Both Palermo Viejo and Las Cañitas are near the D subway line, but restaurants are often quite far from the metro stations. The long walk and the fact that the subte closes at 11pm mean you are better off taking a cab.
While I highly recommend the restaurants listed, note that you should arrive by cab if you're coming for dinner and have the restaurant call a cab for you when you leave. The area is considered dangerous at night and you should not wander around.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.