Cut the pork crosswise into even 1-inch thick pieces. Set aside. In a large bowl, stir together the garlic, five-spice powder, sugar, sesame oil, soy, ketchup, honey, and hoisin. Add the pork to the marinade and turn to coat well. Cover and leave at room temperature for about 1 hour, turning the meat 2 or 3 times. For deeper flavor, transfer to a zip-lock bag and refrigerate overnight. Remove pork from marinade and reserve marinade for basting the pork while cooking.
To make the steamed buns, place the water in a bowl of a stand mixer. Sprinkle the yeast over the top and stir to dissolve. Combine all the dry ingredients and add to the water with the melted lard. Stir with the dough hook on low speed for 8-10 minutes. Cover with plastic wrap and allow to rise until double in volume, about 1 ½ hours. Punch the dough down with your fingertips. Roll dough out on a lightly floured work surface about a quarter inch thick and cut into 3 inch circles.
Roll each circle out further into and oblong shape and fold over on top of themselves. Cut sheets of parchment into four-inch squares to set the buns on the parchment squares and then place on a sheet pan. Cover with plastic wrap. Allow to rest for 30 minutes. Set in a steamer basket and steam for 10 minutes. Repeat until all the buns are steamed.
Light the grill and lightly oil the grates with vegetable oil. Grill the pork over a medium-hot fire for 16 to 20 minutes, turning frequently. During the last 5 minutes, baste with the reserved marinade; cool on a rack. Pork is done when it looks glazed, is slightly charred. Let rest for 10 minutes. Slice thinly.
To serve, re-steam the buns to warm them through. Open the buns up and spread a teaspoon of hoisin sauce on the bottom. Top with a slice of pork, and some green onion and cucumber. Serve while still warm.
Enjoy with a glass of Cakebread Cellars Annahala Pinot Noir.