Okay, so we've been to 2 new (at least new to us) Cantonese Dim Sum restaurants this past month. Both are quite good as the older restaurants have all gone downhill

1. Foolays (or foolais?) at Recoleta esquina Bellavista (on Artesanos). A brand new blue glass building, on the 3rd floor w/ free basement parking. If you're familiar with the old Sheng Xing, you'll see many familiar faces and the food is better!
2. Don't remember the Spanish name

but it's at Indenpendencia and Palermo. There's a large pay/parking in front and the restaurant is on 2nd floor of a small galeria/mall. Their food is very authentic!

Highly recommend this one, it was super crowded this past Monday, with everyone speaking Cantonese. Not to get confused with the large chinese restaurant a block away called China Town.
Think both of them has metro nearby.