In a large bowl, dissolve yeast and sugar in warm water.
Stir in 2 cups of flour, the lard, and salt.
Gradually stir in the remaining flour, 1/2 cup at a time, mixing well after each addition.
Once the dough comes together, turn it out onto a lightly floured surface and knead until smooth and elastic, about 8 minutes.
Lightly oil a clean large bowl, place the dough inside, and turn to coat it with oil.
Cover with a damp cloth and let it rise in a warm spot until doubled in size, about 1 hour.
Lightly grease two 9x5-inch loaf pans.
Punch down the risen dough, transfer it to a floured surface, and divide it into two equal pieces.
Shape each into a loaf and place them in the prepared pans.
Cover again with a damp cloth and allow them to rise until nearly doubled, about 40 minutes.
Meanwhile, preheat your oven to 425°F (220°C).
Once ready to bake, place the loaves in the oven, immediately lower the temperature to 375°F (190°C), and bake until the tops are golden brown and the bottoms sound hollow when tapped, about 30 minutes.
Cool on a wire rack before slicing.