Argentine Grilled Tri-Tip
I am sorry but saying "From Buenos Aires to Patagonia" is like saying from Miami to NY, you are missing most of the country...
Empandas in Argentina are very different in each province and the most famous ones are the ones made in the wood oven and filled with meat.
I am 23 years old, I was born and raised in Argentina and I cook in a hotel in Salta. I eat asado two times a week and I have never tried or seen anything similar to the picture you have placed above. The most common cut is the "costilla" (rib) of different sizes, usually larger (around 10 to 15 cm) at home reunions and smaller (around 5cm) at cheap restaurants.
Congratulations for the article, all the other items are well described and very usual in Argentina, but the empandas are kind of a tricky subject and you have chosen the most unusual; the asado is defintely wrong...asking a chef in San Francisco was, regrettably, a bad choice.