Decide whether you’ll proof the buns overnight or on the same day. See the notes above for more detail.
Heat the plant milk until it’s warm enough to be pleasant without burning your finger. Add the sugar and yeast and set it aside for the yeast to proof. If you have no action after 10 minutes, start again with new yeast.
In a large mixing bowl, combine all the dry ingredients and the orange zest. Whisk to combine.
Once the yeast has bloomed, add it to the dry mixture along with the water and oil. Whisk until there are no lumps, then cover and place in the fridge for 1 hour or overnight.
After the fridge rest, the dough should look spongy and be borderline wet. Stir in your add in ingredients.
Using oiled hands, divide the mixture into 8 or 9 buns, rolling them into balls quickly between oiled hands. Place them snug in a lined baking dish with walls (it will help support them rise upwards) with a little space between them to rise. Alternatively you can bake them in muffin holes or a small casserole dish.
Cover them and allow them to rise for an additional hour.