[header] How to make mexican polvorones [title] Place the pecans in a food processor fitted with a steel blade and coarsely chop them. [step] Then add the confectioner's sugar to the food processor bowl and continue processing until the pecans are finely ground but not smooth. [title] Combine the flour, the pinch of salt and the baking soda in a large mixing bowl using a flat plastic spatula or wooden spoon. 
[title] Add the butter chunks to the flour mix. [title] Add the shortening , 1 teaspoon at a time, until you have added all of it to the flour mixture.