Cut off the top and bottom as well as the outermost leaves of the lemongrass, chop the rest very finely. Chop ginger (1-2 cm) and garlic cloves. Mash everything together in a mortar to a paste. Then add the sambal oelek, turmeric, coriander, cumin and salt and mix.
Cook the pasta in boiling water for about 2 minutes, rinse and drain.
Cut the leek into strips (approx. 4 x 0.5 cm) down to the roots and hard, green areas. Quarter the oyster mushrooms, cut the peppers into fine strips.
Cut the chicken breast fillet into cubes and fry it in well-heated oil in a wok or pan until crispy, remove and drain on a kitchen towel and sprinkle with a little salt.
Heat a little oil in the wok and heat the paste from the mortar for about 2 minutes. Add vegetables and mushrooms and fry for another 3-4 minutes. Add the coconut milk and bring to the boil. Now add the noodles and the chicken breast cubes and warm up.
Season with ketjap manis (sweet soy sauce) and serve.