Warm the soy milk in the microwave for 1 minute and 30 seconds. Make sure it is warm, like bathwater, not too hot or it will kill the yeast.
In a large bowl, add the warm soy milk, sugar and yeast. Let it sit for 5 minutes. The yeast should get a bit foamy on top.
To the yeast mixture, add the melted vegan butter, salt and 4 1/2 cups of flour. Stir with a large spoon until the mixture comes together. Add additional flour, 1/3 cup at a time, as needed until the mixtures pulls away from the sides of the bowl. It should still be soft and slightly sticky.
Turn the dough out onto a lightly floured surface and knead for 3-4 minutes, until you have a fairly smooth ball of dough. Place the dough back in the 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.