Place the rice noodles in a heatproof bowl and cover with boiling water. Place the shiitake mushrooms in a separate bowl and cover with boiling water. Leave both for a few minutes while you prepare the other ingredients (you may want to drain the noodles sooner, check package instructions).
Peel and de-seed the pumpkin, if not already done so, and cut the pumpkin into matchsticks. Dice the onion finely, finely slice the green onion, keeping a few green slices to one side. Crush the garlic and finely chop the dried shrimp so they are almost like a powder.
Once the shitake mushrooms are soft, remove form the water but don't discard the liquid (you will use later). Halve then finely slice the mushrooms.
Heat the oil in a wok or large skillet/frying pan and add the onion. Cook a minute or two then add the garlic, green onion, shitake mushrooms and dried shrimp . Cook another minute or two until they are aromatic and the onions are softened, but take care not to burn the garlic.
Add the pork and brown the meat all over, then add the pumpkin and mix through. Pour in the soy sauce, oyster sauce, sugar, white pepper and salt and mix well.
Add in the drained noodles and the measured, reserved liquid from soaking the mushrooms (top up if needed) and mix, being relatively gentle so you don't break up the noodles. Cover and cook for around 2 - 3 minutes until the pumpkin is tender and cooked, but try not to cook longer to avoid it becoming mushy. If you reserved any green pieces of the green onion, add in, mix then serve.