Heat the oven to 375ºF.
To make the oyster mushroom bacon, combine the oils, liquid smoke and salt in a large bowl. Toss the mushrooms to coat. Place the mushrooms gill side down in a cast iron pan or baking sheet, taking care not to crowd them. After 10 minutes, if there is a lot of moisture in the bottom of the pan or sheet, remove from the oven and tilt to collect and discard with a spoon.
Return to the oven and bake for 5 minutes more, watching them carefully to avoid burning. Flip, then bake for about 5 minutes more, or until they have a nice color around the edges, keeping a close eye on them. Transfer to paper towels to drain slightly and allow them to crisp up.
Combine the cucumbers with the remaining sugar and salt in a small mixing bowl and toss to coat. Let sit for 5 to 10 minutes. Use right away or refrigerate for up to 4 hours.
Stir together the yeast and 1 1/2 cups room temperature water in the bowl of a stand mixer fitted with a dough hook. Add the flour, sugar, salt, baking powder, baking soda and coconut oil and mix on the lowest speed setting for 8 to 10 minutes. The dough should gather together into a ball on the hook. Lightly oil a large bowl and put the dough in it, turning it over to coat it with the oil. Cover the bowl with a dry kitchen towel and put it in a warm place and let the dough rise until it doubles in size, about 1 hour 15 minutes. Punch the dough down and turn it out onto a clean work surface. Using a sharp knife, divide the dough in half, then divide each half into 5 equal pieces. Gently roll the pieces into logs, then cut each log into 5 pieces, making 25-30 pieces total. They should be about the size of a Ping-Pong ball and weigh about 25 grams each. Roll each piece into a ball and set them on baking sheets. Cover them loosely with plastic wrap and let them rise for 30 minutes. While they're rising, cut out 35 4-inch squares of parchment paper. After 30 minutes, use a rolling pin to roll each ball into a 4-inch-long oval. Brush lightly with vegetable oil, lay a chopstick horizontally across the center of the oval and fold the oval over onto itself to form a bun. Gently pull out the chopstick, leaving the bun folded, and transfer it to a square of parchment paper. Put it back under the plastic wrap and form the rest of the buns. Let the buns rest for 30 to 45 minutes: they will rise a little. Set up a steamer on top of the stove. Working in batches so you don’t crowd the steamer, steam the buns on the parchment squares for 10 minutes. Remove the parchment. You can use the buns immediately or allow them to cool completely, then put them in plastic freezer bags and freeze for up to 2 months. Reheat frozen buns in a stove top steamer for 2 to 3 minutes, until puffy, soft, and warmed all the way through. Freeze half the buns in airtight bags for another time.
To serve, assemble the steamed buns with hoison sauce, one or two pieces of mushroom, cucumber, something pickled, scallions and fresh cilantro. Serve warm.