Begin by adding your warmed oat milk and yeast to a large mixing bowl. Let sit for 3-5 minutes to make sure the yeast is activated. You will be able to tell if it's bubbling. If using instant yeast, you can skip this step and add the yeast directly to the mix with the flour and salt.
Next, add the melted vegan butter, sugar, orange juice, orange zest, and vanilla to the large mixing bowl and whisk together to combine.
Mix the salt into the bowl of flour and then begin to gradually add the flour/salt mixture to the bowl of wet ingredients about ½-1 cup at a time. Start with 3 ½ cups of flour and add up to 3 ¾ cups if the dough is still too sticky.
Once all the flour has been added in, knead the dough. If using a standing mixer, switch the attachment to the bread hook and knead for 5-10 minutes until elastic. If you are kneading by hand, knead on a lightly floured surface for 10-15 minutes or until the dough is elastic and significantly less sticky. The dough is done being kneaded once it can be stretched without easily tearing and is smooth and tacky but not sticky.
Form the dough into a large ball and place it in a well oiled bowl. Cover and place the bowl of dough in a warm place to rise for 1-2 hours until the dough has doubled in size. I like to test my dough by "poking" it with a finger. If it doesn't bounce back and stays indented, it is ready. It is also important to not “overproof” the dough as it can turn sour from the yeast turning the sugar into alcohol, so do not let the dough sit too long.