Whisk together the water and yeast in a small bowl or liquid measuring cup. Let it sit for a few minutes while you prepare your dry ingredients.

Stir the flour, sugar, salt, and baking powder together in a large mixing bowl. 

Stir 1 tablespoon of oil into the yeast and water mixture, then add the mixture to the dry ingredients. Stir to form a soft dough.

 Transfer the dough to a lightly floured work surface and knead it for about 7-8 minutes, until smooth and elastic.

Lightly oil a medium bowl, roll the dough into a ball and place it in the bowl. Cover with a towel and place it in a warm spot to rise until doubled in size, about 1-2 hours.

While the dough rises, mix the water, vinegar, sugar and salt together in a medium bowl, stirring until the sugar dissolves. Add the veggies and allow the mixture to sit while you make the filling and finish making the buns.

Stir the soy sauce, vinegar, maple syrup, sesame oil, sambal oelek, and liquid smoke together in a small bowl.

Coat the bottom of a large skillet with oil and place it over medium heat.

When the oil is hot, add the mushrooms in an even layer. Cook the mushrooms for about 4 minutes, flip and cook 4 minutes more, until lightly browned.

Add the sauce to the skillet and flip a few times to coat the mushrooms. Allow them to continue cooking until the sauce is thick and forms a sticky coating, about 3 minutes more.

Remove the skillet from heat and transfer the mushrooms to a plate.

Once the dough has doubled in size, divide it in half. Remove half from the bowl and divide it into fifths.

Roll one of the fifths into a ball, then flatten it with your hand.

Use a rolling pin to roll the ball into a 4-5 inch round. Brush the top with oil, fold it in half, and transfer it to a piece of parchment paper (I like to to place the parchment paper in the steamer, so I don't have to move it again later). Make sure not to crowd the dough rounds.

Repeat for the remaining pieces of dough, then remove the other half of the dough from the bowl and repeat. You should have 10 rounds.

Cover the dough rounds and let them rest for 15 minutes. 

Transfer the parchment rounds to the bamboo steamer if they're not already there. They may not all fit — just work in batches of that's the case. 

Layer the tiers in your steamer, place the lid on it, and place it over a large pot of water. Bring the water to a boil and steam the buns for 8 minutes.

Very carefully remove the lid and remove the buns from the steamer. 

Slather the insides of the buns with hoisin sauce, then stuff with mushrooms, pickled veggies, peanuts, scallions and cilantro. Serve.