Prepare the buns: Heat the nondairy milk to 100°F to 110°F (37°C to 43°C). Mix the warm milk with the yeast and ½ tablespoon of the sugar. Set aside to proof for 10 minutes, until foamy.

In a large bowl, whisk together the flour, baking powder, salt, and remaining tablespoon of sugar. Pour in the proofed yeast mixture, 3 tablespoons of water, and 2 tablespoons of the oil. Mix with a rubber spatula until the dough begins to come together.

Pour the dough out onto a clean, very lightly floured surface and knead with your hands for 5 to 7 minutes, until the dough forms a smooth ball. Brush the bowl with the remaining ½ teaspoon of oil and place the dough back in the bowl. Cover with a towel and set aside to rise for 1 hour. Note: It will not double in size.

After the dough has risen, remove it from the bowl and place it on a clean surface. Use a rolling pin to roll out the dough to ¼ inch (6mm) thick. Use a 3½-inch (8.8cm) biscuit cutter or large glass to cut out circles, gathering up the scraps and rerolling the dough as needed, until you have a total of 12 dough circles.

Lightly brush the tops of the circles with oil and fold in half. Then very gently roll the buns to elongate them into a slightly oval shape. Place on a rimmed baking sheet, cover with a towel, and allow to rise one final time for 45 minutes.

About 20 minutes before the buns are done rising, prepare the tempeh: Use a sharp knife to cut the tempeh crosswise into 15 rectangles. Then cut each rectangle in half, resulting in 30 small tempeh squares. Place the tempeh in a large nonstick frying pan with ½ cup (120 ml) of water. Cover with a lid and steam the tempeh for 15 minutes over medium-high heat, or until it looks a bit puffy and all water has been absorbed. Once the tempeh is done, reduce the heat to medium and pour the oil into the pan; sauté for 5 to 7 minutes, until golden and crispy.

In a small bowl, mix together the gochujang paste, maple syrup, soy sauce, garlic powder, and 1½ teaspoons of water to form a thick sauce. Pour it over the tempeh and cook for 1 minute, tossing to coat all the pieces evenly with the sauce.

Line both steamer baskets with parchment paper, then place 4 buns in each basket. Bring a sauté pan or wok filled with 6 cups (1.4 L) of water to a boil over high heat. Reduce the heat to medium to maintain a vigorous simmer and place one steamer basket in the pan. Cover with the lid and steam the buns for 10 minutes. The buns will appear shiny on the outside and will have increased slightly in size. Do not open the steamer to check on them. Remove from the heat and carefully take the buns out. They will be very hot. Repeat with the second basket of uncooked buns.

To assemble the bao: Open the buns and place a few pieces of cabbage, carrot, and cucumber along with 2 to 3 pieces of tempeh in each. Sprinkle with the green onions and sesame seeds and serve.