Microwave the soy milk for about 1 minute and 30 seconds, until warm but not too hot or it will kill the yeast.
In a large bowl, add the warm soy milk, sugar and yeast. Stir a little bit; the yeast will get foamy.
To the yeast mixture, add the melted vegan butter, salt and 4 1/2 cups of flour. Stir with a large spoon until it comes together. Add additional flour, as needed. Alternatively, use a stand mixer with a dough hook and mix on low until the mixture pulls away from the sides of the bowl. It should still be soft and slightly sticky.
If using a stand mixer, simply mix with the dough hook until you have a smooth ball of dough. If not, turn the dough out onto a lightly floured surface, and knead for 3-4 minutes until you have a smooth ball of dough.
Place the dough in a lightly oiled bowl, cover with a towel and let it rise in a warm place for 20 minutes. Here's what I do: Turn the oven to 170 degrees F. Once heated, turn it off, place the covered bowl inside the oven, and leave the oven door cracked.
Preheat the oven to 375 degrees F (skip this for make ahead option) and grease a 9x13 inch baking dish.