In a small bowl or measuring cup, whisk together lukewarm water and soy milk with active dry yeast. Allow to proof for about 5 minutes, or until foamy.
Meanwhile, in the bowl of a stand mixer, stir together bread flour, granulated sugar, and fine salt to combine.
Pour the foamy yeast mixture into the dry ingredients. Then add in the softened butter. Use the dough hook attachment and mix together on medium speed until the ingredients come together into a shaggy dough.
After the dough has all come together (no dry streaks), knead for an additional 6-8 minutes, until the dough goes from shaggy to smooth and elastic. It should easily clear the sides of the bowl. If the dough seems too sticky, knead in extra flour 1-2 tablespoons at a time until the right texture is achieved.
Shape the dough into a ball and place it back into the mixing bowl. Drizzle with a little bit of vegetable oil and turn it around in the bowl till the dough is lightly coated with oil. Cover with a plate, plastic wrap, or a damp kitchen towel and place in a warm spot to rise for about 1 hour, or until doubled in size. (It can take longer if the room is chilly.)