Preheat oven to 425ºF. Line a baking sheet with a silicone mat or parchment paper.
Cut the butter into pieces. Set aside in the fridge.
In a large mixing bowl, combine flour, baking powder, salt, and sugar.
Remove the butter pieces from the fridge. Using your fingers, work the butter pieces into the flour until thing slices and pea-sized pieces remain. Work quickly to prevent the butter from melting due to the heat from your hands.
Create a well in the middle of the mixture. Pour the soy milk into the well. Using a fork or other utensil, slowly begin incorporating the soy milk into the flour mixture until a dough forms. Fold the dough over itself a few times in the bowl.
Turn the dough out onto a floured work surface and knead a couple times until the dough comes together.
Use bench scraper to form dough into a 4" x 8" rectangle.
Fold dough into thirds using a letter fold.
Rotate the dough 90º and form the dough into a 4" x 8" rectangle. Fold dough into thirds again using a letter fold.
Rotate the dough 90º and form the dough into a 4" x 8" rectangle. Cut the dough into 8 equal pieces.
Transfer the pieces to the lined baking sheet. Brush the tops of each piece with melted butter.
Bake for 20-25 minutes, or until the tops are golden brown.