Set the corn husks in a bowl of warm water to re-hydrate them.
Mix a tablespoon of stock and the shortening in a medium to large bowl. Mix in the masa harina, baking powder and salt. Continue adding stock until you get a sponge like dough. Set aside.
De-seed and de-stem the chili pods. Simmer in a saucepan with 2 cups of water for 30 minutes. Allow to cool.
Use a food processor or blender to puree the chilies and water. Strain and add the salt.
Shred the cooked pork tenderloin in a large bowl and stir in the chili sauce.
Remove the corn husks from the water and allow them to dry a bit. Spread them out and spread the dough on top, leaving a 1/4 inch space on the outer edges uncovered.
Add a tablespoon of the meat mixture and spread it out a bit over the dough mixture. Fold the husks in, starting with the sides, and flip to close.
Place the tamales in your steamer and allow to steam for 1 hour. Carefully unwrap the husks, remove the tamale and enjoy.