Preparation Working in batches, cook three-quarters of green beans in a large pot of boiling salted water until crisp-tender, about 3 minutes per batch. Transfer to a bowl of ice water; let cool. Drain and pat dry; trim stem ends. Combine mushroom soy sauce, black vinegar, rice vinegar, and sugar in a small bowl, stirring to dissolve sugar. Set mushroom XO sauce aside. Trim stem ends of remaining uncooked green beans. Heat 1 Tbsp. oil in a large skillet over medium-high. Cook beans, tossing occasionally, until blistered in spots and crisp-tender, about 5 minutes. Transfer to a plate. Add remaining 1 Tbsp. oil to same skillet and cook king trumpet and shiitake mushrooms, tossing occasionally, until browned and tender, about 5 minutes. Remove skillet from heat and carefully add brandy away from heat source. Return skillet to heat and tilt to ignite brandy. Once flames have subsided, add shallot, chile, garlic, dried shrimp, half of scallions, and reserved XO sauce. Cook, tossing occasionally, just until aromatics have softened, about 3 minutes (there should still be some liquid in the pan). Add chile oil and all of the green beans and toss well to combine. Serve topped with remaining scallions. Ingredient InfoBlack (Chinkiang) vinegar is an aged vinegar made from glutinous rice and malt. It can be found at Asian markets.