How to Make It
In a large bowl, stir the masa with the hot water until evenly moistened. Knead several times to make a smooth dough.
In a standing mixer fitted with the paddle, beat the lard with the butter at medium speed until smooth, about 2 minutes. Add the salt and baking powder and beat at medium-low speed until incorporated. With the machine on, add the masa in 4 batches, beating until smooth and scraping down the bowl occasionally. Pour in the stock in a steady stream and beat until the dough is fluffy and soft, about 2 minutes; it should have the consistency of thick corn bread batter. Refrigerate the tamale dough in the bowl for 30 minutes.
Return the bowl to the mixer and beat the dough at high speed for 1 minute before assembling the tamales.