Start by combining all the dry ingredients in an appropriately-sized mixing bowl and disperse evenly by hand.

Next, drizzle the warm water, a little bit at a time, while squeezing the mixture together with your other hand. The mixture should be somewhat malleable, almost like the consistency of a soft play dough. The amount of water used will differ slightly every time, so add a little at a time until the consistency described is achieved.

Form dough into a ball and then rub lard over the surface. Flatten dough in bowl, fold it over on top of itself and then reform it into a ball as shown in the pictures below. This will help to incorporate the fat randomly into the dough, which is important for an open, airy texture. 
Pull off a piece of dough that is the appropriate size for your final application. For the chalupa shells that we use to serve our halibut ceviche, we use a 25g piece which is just short of an ounce by weight. The piece of dough is then rolled into a ball and flattened out by pressing the round piece of dough between the palms.

Continue to "patty" the dough back and forth between your palms until the dough is evenly flat. Because you are not using a tortilla press or a rolling pin, the dough will naturally be thicker then that of a tortilla. At this point, to make sure each chalupa shell is the same size, we punch out a circle using a 2.5"/6.5cm diameter ring mold. This is purely for aesthetics, and you can form or cut your chalupa shells to any size that you wish.

The finished product should look like this:

You can also easily make a larger chalupa that is then fried and used much like a tostada. The process is exactly the same as described above, only you'll start with a larger piece of dough, and cutting it with a ring mold isn't necessary.

Whether you're making a large or a small chalupa shell, they're best fried and served fresh. We fry our shells in 375°F/190°C canola oil for about 2-3 minutes on each side, or until they puff up and are an even golden brown. If you want it to taste more like grandma's version, then I would recommend frying them in lard.