By this time, the potatoes should be just about ready to be drained. Drain the potatoes, return the potatoes to the pot and mash over low heat, or mash in the bowl of stand mixer fitted with the paddle attachment, adding the cream and 2 teaspoons salt.
I made tacos like this on a weeknight when cooking was the last thing on my list. We had leftover sweet potatoes already cubed, and this was so quick to put together. Delicious! Black beans and sweet potatoes are a great flavor combo.