Pick Market has a few different locations in Buenos Aires which you can find details of on their website. This one is my local so I'm sharing info on it... It's basically a smaller version of Whole Foods and I love the fact that everything is so fresh and good for you.
If you're keen to cook something yourself when in Buenos Aires then this place is a good option for some healthier treats and if you're wanting a change from steak! You can sit in and eat here too - just pick out different bits you want (including artisan beer and fancy wine) then head upstairs to the terrace to enjoy your feast.