Bring saucepan of water that will fit under bamboo steamer to boiling. Line each layer of steamer with cabbage leaves or parchment paper.
Separate dough into 8 biscuits. With fingers, flatten each into round about 1/2 inch thick. Fold over to form half-moon shape; place in steamer. Set steamer on top of saucepan of boiling water. Steam 10 minutes; cool completely.
While buns are steaming, heat oven to 350°F. In 8-inch skillet, heat olive oil until it begins to shimmer. Add tofu (it should immediately start to sizzle). Cook 2 minutes on each side or until a thin, crispy crust forms. Place in baking dish.
In small bowl, mix soy sauce, sesame seed, sesame oil, 2 green onions and the garlic. Pour over tofu. Bake 15 minutes.
To serve, cut each bun to form pocket for fillings. Spread small amount of hoisin sauce in each bun. Stuff each with cucumber slices, green onions and a slice of tofu.