First, mix the tamale flour (or masa) with the pork lard until well combined. Gradually add the hot broth until you have a 'dry' dough (it shouldn't be soupy). Sometimes 4 1/4 cups (1 liter) of broth is enough, sometimes less, and sometimes you may need to add a bit of hot water. Once mixed, add the baking powder. If using tamale flour, you can add the baking powder directly to the flour before mixing. Set aside.

Cook the calabaza de castilla (Mexican pumpkin), seeded, in salted water (you can do this while preparing the dough). Chop the tomatoes and onion. Separately, boil the guajillo chiles (note: if you only have the hot variety, you can add a little piloncillo to the boiling water to reduce the heat).

Once the chiles are boiled, blend them with a little of their cooking water, the garlic, onion, tomato, and cumin to make a sauce. Peel the cooked pumpkin (this is easy with a spoon when it's well cooked) and cut into cubes. In a food processor, grind some of the dried shrimp into a powder and set aside. In a large skillet, sauté the pumpkin, then add the fresh shrimp and cook briefly. Strain and add the sauce, then add the shrimp powder. Let it simmer until the fresh shrimp are cooked and the pumpkin forms a paste.

Cut and toast the banana leaves to make them flexible and prevent tearing. Do this by placing the shiny side of the leaf over the heat; the dull side will darken. This only takes a few seconds—just enough to make them flexible, but be careful not to burn them. You can do this on a griddle or directly over a stove burner.

Prepare a tamale steamer or a large pot with a steaming rack. Spread the dough on the shiny side of the banana leaf, using a wooden spatula, aiming for the center of the leaf. Make a small 'well' in the dough and place the filling inside (about 2 heaping tablespoons per tamale). Arrange the tamales with the folded side up, around the sides of the pot, leaving a space in the center. Continue until the pot (or pots) are full.

Steam for 1 to 2 hours, making sure the water doesn't dry out and adding more as needed. After about 1 hour to 1 hour 15 minutes, check one of the tamales on top; if it's cooked through, the rest are ready. Enjoy! If you have any questions or comments, I'd be happy to answer them.