Heat the onion, garlic, and spices in the olive oil on a large pan for 5 minutes, stirring often. Add the potatoes and cook for 5 minutes, then add the beans and cook a final 5 minutes. Set aside.

Make the flax "egg": in a small bowl, combine the flax seeds with 3 tbsp. warm water, and set aside for a few minutes, stirring often to help thicken.

In a food processor, combine the flour, salt, baking powder and butter, processing for a few minutes until the butter combines with the dry ingredients.

Add the flax mixture and the milk to the processor, and combine.

Remove the dough from the processor, put it on a floured surface, and form it into a ball. Spray coconut oil or another oil in a large bowl, and place the ball of dough in the bowl. Cover with plastic wrap, and set in the fridge for about 20 minutes.

Flour a large surface, and roll out the dough to about 1/8" thickness.

Cut the dough into circles (I used the back of a bowl and a sharp knife to cut my circles).

Add the filling, and fold over, sealing the edges with your fingers, or a fork, or use a pastry press (I bought mine for about $5 on Amazon).

Place the empanadas on parchment paper and put back in the fridge for another 20 minutes (or longer, you can bake them the next day if you wish).

Meanwhile, heat your oven to 400 degrees.

Melt about 1 tbsp. vegan butter and use a pastry brush to brush each side of the empanadas.

Place the empanadas on a baking sheet and bake, about 15 minutes each side, until the empanadas are golden.

Serve with your favorite salsa, vegan sour cream or guacamole.