Pour 500g stone-ground whole wheat flour into a clean large bowl. Add 1 pack of active dry yeast, 1 tsp lard, and 5g granulated sugar (if using). Stir all dry ingredients thoroughly with chopsticks to evenly distribute the yeast and prevent uneven fermentation.
Gradually pour in 260g warm water, stirring rapidly with chopsticks while pouring, until the flour forms uniform clumps with no visible dry particles. (If the flour is highly absorbent, add 5-10g more warm water; if too wet, sprinkle in a little extra whole wheat flour until the mixture can be shaped into a dough.)
Knead the clumpy flour into a dough by hand. Whole wheat flour, due to its wheat bran content, takes a bit more patience to smooth out. Knead repeatedly for 5-8 minutes until the dough is mostly smooth, non-sticky to your hands, and doesn’t stick to the bowl (the "three smooths"—bowl smooth, hand smooth, dough smooth—are ideal for better ductility and fluffier steamed buns).