Heat oil in a pan. Add cashew nuts and fry till they turn light brown. Take out on a plate and keep aside.
Add dried chilies to the same pan and saute for a few seconds.
Add grated ginger, garlic, and galangal. Saute for around a minute or till they become fragrant.
Next, add the diced onion and spring onion white part. Stir fry till they become translucent.
Crush the kaffir lime leaves and lemon stalk with your hands or by using a mortar and pestle and add to the pan. Don't make small pieces of leaves and stalk as they will be removed from the dish later. Saute for a few seconds and then add the mushrooms
Saute the mushrooms till their moisture gets evaporated.
Next, add the bell peppers and stir fry for around 3-4minutes on high flame.
Mix soy sauce, vinegar, salt, and sugar in a bowl and add to the pan. Mix well.
Add the spring onion greens, stir fry for about a minute and then switch off the gas. Remove the kaffir lime leaves and lemongrass stalk from the pan.
Finally, add fried cashew nuts and mix.
Squeeze in fresh lime juice and serve.