Pericles' last link, to Casa Felix, is one of the best restaurants in Buenos Aires, although its not a restaurant at all.
Diego Felix cooks for a few people, in his house, and he is an incredible cook.
His main course is usually fish, no red meat, but the meals are 5 courses, and the other 4 are generally vegetarian, but, on request, he will do vegetarian or vegan meals.
100 pesos, and worth every penny. Anywhere in North America or Europe, a meal like this would cost $100 or 100 euros.
This is a world class chef, cooking in an intimate setting, and explaining each dish to you, and is one of the best meals you will ever eat.