I also found a good source of sweetened condensed milk in case I don't feel like making it from scratch and superfine sugar for candy making.
Sadly, four stores, two metro rides, and lots of walking - and I still have no source of cream of tartar. Tomorrow, I will try one more bakery supply store downtown, and then if I still have no luck, it might be time to order from Amazon.es.
In addition to my shopping, I did get to see some of the Christmas lights in the small town on the other side of the bridge.
And, near the end of my adventure, I came upon a group of carolers near our home - a nice surprise. I listened for a while, snapped a quick photo, and then headed in with the groceries and let Albert know they were there - he went out and took a careful video.