In a microwave-safe container, melt your soymilk and margarine together in the microwave for about 30-40 seconds. Test the temperature of your melted margarine/soymilk mixture with your finger and make sure that it is only lukewarm, so you don't kill your yeast.
Combine your margarine/soymilk mixture with lukewarm water and active yeast and give it a whisk. Let the yeast mixture sit for about 5 minutes to make sure that the yeast starts to get slightly frothy.
Now, whisk in salt, vanilla, cornstarch, and sugar.
Finally, add your flour, and gently knead everything together for 2-3 minutes until a sticky dough forms. Because most amateur bakers (including me) don't use kitchen scales for flour measurements, there is always the chance that your flour will settle more or less and you will need to add either a few teaspoons of water or flour to make the dough just right. For this dough, you want it just a little more moist and sticky than regular bread dough.
Now, place your dough back in a large bowl, cover with plastic wrap or a towel, and let it rise in a warm place for 60 minutes. I like to turn my oven up to 350 degrees Fahrenheit for about 1 minute, then turn it off. This makes a perfectly warm environment for my dough to rise--just make sure your oven is turned OFF before putting your dough inside. :)
Remove your dough from the mixing bowl and roll it out on a lightly floured surface to form a 12 inch by 22 inch rectangle.
In a small bowl, combine filling ingredients: softened vegan butter, brown sugar, cinnamon, salt, and finely diced apple. Now, spread this mixture all over your dough--all the way out to the edges.
Spread filling onto your rolled out dough, as described in the filling recipe below.
Now, using a pizza cutter, cut your dough lengthwise into 4 strips.
Stack those strips on top of each other for form one long stack of strips. (It's going to be messy. Many apple pieces will fall off, just put them back in when you're done.)
Using a sharp serrated knife, slice 6 equal square-shaped stacks of dough. Put all the stacks on top of each other to form a tower of sorts. In one brisk movement, carefully pick up the tower and place it lengthwise, cut sides up in an oiled bread pan. Don't worry about making your squares perfect symmetrical. In my opinion, the bread looks nicer when your dough slices are a little crooked and uneven. Your finished product should look like a loaf of many slices of bread lined up in the pan.
Place the loaf in a warm place to rise for 30 minutes.
After 30 minutes, remove your dough from the turned-off oven (if that's what you've used), and preheat your oven to 325 degrees Fahrenheit.
Bake your loaf at 325 degrees Fahrenheit for about 40 minutes. Stab it with a fork or toothpick to check for uncooked dough. If everything is cooked, allow your bread to cool for a few minutes before removing it from the pan and serving.
I loved this bread without any caramel on top. However, if you're going to take this pull-apart bread to another level of amazingness, whip up a batch of vegan coconut caramel sauce to drizzle on top. See instructions below.