1½ pounds (700 g) king oyster mushrooms, tough ends removed and discarded
¼ tsp. salt
¼ cup (60 ml) light soy sauce
2 Tbsp. Chinese sesame paste (or unsweetened natural peanut butter or tahini)
2 Tbsp. Chili Oil, or to taste, plus more if needed
1½ Tbsp. Chinkiang vinegar
4 tsp. sugar
2 cloves garlic, grated
2 tsp. grated ginger
½ tsp. freshly ground Sichuan peppercorns
1 small cucumber, julienned
Chopped scallions, for garnishing
Prepare a steamer by bringing 2 to 3 inches (5 to 7.5 cm) of water to a boil in the pot.
Shred the mushrooms by first using a fork to carefully score deep grooves along the length of the stems (the grooves will make it easier to pull the mushroom apart by hand). Pull them by hand until they’re mostly thin strips.
Place the shredded mushrooms on a plate that can fit into the steamer. Sprinkle with the salt and toss a few times to mix well. Place the plate inside the bamboo steamer or on the steamer rack, then place onto the pot of water. Steam, covered, for 8 minutes, or until just cooked through. Remove the steamer from the heat immediately. Carefully uncover the steamer and let the steam out. Use oven mitts to remove the plate from the steamer.
In a large bowl, combine the soy sauce, sesame paste, chili oil, vinegar, sugar, garlic, ginger, and Sichuan pepper for the sauce. Whisk to mix well. Taste and add more chili oil, if desired.
Place the cooked mushrooms in a separate large bowl or deep plate. Let them cool to room temperature. Pat dry with paper towels.
Add the cucumber to the mushrooms, drizzle the sauce on top, and toss to mix well. Garnish with the scallions and serve warm, at room temperature, or cold.