Add the soy sauce, beer, brown sugar, garlic, ginger, vinegar, sesame oil and gochujang to a bowl, mix until well combined.
Add the mushrooms to a large Ziplock bag, add the mixture on top, remove all the air. Add to the fridge, marinate for one hour and up to overnight.
Add the sugar, salt, hot water, cloves and peppercorn to a large bowl. Stir until the sugar and salt are dissolved. Add the vinegar and allow to rest for 5 minutes, remove the cloves and peppercorns.
Add the cabbage, onion, mint, cilantro and green onion. Cover and refrigerate for at least one hour and up to several days.
Heat the olive oil in a large skillet over medium-high heat.
Add the mushrooms and marinade. Cook until the marinade has thickened, and the mushrooms have softened about 10 minutes.
Add the mushrooms to the lettuce leaves, top with slaw and chilies (if using).