Make the buttermilk by pouring 1 tablespoon of white vinegar into a liquid measuring cup or a regular 1 cup measuring cup. Add in vegan milk of choice until it fills to 1 cup (you should have 1 cup total). Let sit for 5-10 minutes until the milk has curdled.
Preheat the oven to 425°F and line a muffin tin with liners.
In a microwave safe bowl, add vegan butter and heat until melted. Remove from the microwave, then pour in the oil and sugar and whisk. Add eggs, vanilla extract, and buttermilk and whisk until combined.
Slowly add in the flour, salt, baking soda, and baking powder and continue to mix together until just combined (do not over-mix! It's okay if there are some lumps in the dough). Stir in the chocolate chips.
OPTIONAL: Let the muffin batter rest on the counter for 1 hour (this creates taller muffins). Fill the muffin tins all the way to the top of the liners. Generously sprinkle with coarse sugar and top with more chocolate chips if desired.
Bake the muffins for 5 minutes at 425°F. After 5 minutes, leave the muffins in the oven and lower the oven temperature to 350°F. Bake for an additional 10-16 minutes, or until a toothpick inserted in the centre of the muffins comes out clean. Enjoy!