If using dried shiitakes, soak them in hot water until softened, about 30 minutes. Drain well. For dried and fresh mushrooms, remove and discard the woody stems. Slice the caps thinly.
Put the vermicelli in a heatproof bowl with enough very hot water to cover. Soak until softened, 8 to 10 minutes. Drain well. If you like, cut the noodles with a knife or kitchen scissors to shorter lengths (4 or 5 inches) at this time. Loosen the noodles and spread them on a dishtowel to dry while you proceed.
Put 1 Tbs. of the oil in a small saucepan and heat over medium heat. Add the curry powder and half of the minced garlic and sauté for 20 seconds. Add the broth, soy sauce, sugar, chile paste, and salt. Cover and cook for 5 minutes. Remove from the heat and set aside.
Heat a large wok or sauté pan over high heat, add 1 Tbs. of the oil, and tilt the pan to coat. When hot, add the remaining garlic and the ginger. Stir-fry until the garlic is golden, 10 to 20 seconds. Add the celery, onion, green pepper, bean sprouts, scallions, and reserved mushrooms. Stir-fry until crisp-tender, 2 to 3 minutes. Transfer the vegetables to a plate and set aside.
Heat the remaining 1 Tbs. oil in the pan over high heat. When the oil is hot, add the shrimp and stir-fry until just cooked through, 1 to 2 minutes. Add the barbecued pork; toss well. Add the noodles, vegetables, soy-curry mixture, and oyster sauce. Toss to mix thoroughly and to coat noodles with the sauce. Serve immediately.