Peel and finely chop the ginger.
Heat the vegetable oil in a large pan over medium heat. Add the ginger and cook for about a minute until fragrant.
Bruise the lemongrass with the side of a knife and add it to the pan.
Stir in the Thai red curry paste along with 50ml water. Cook for 1–2 minutes, stirring.
Add the coconut milk, salt, palm sugar and fish sauce. Stir well, bring to a gentle simmer, then reduce the heat to low.
Chop the green beans and red pepper into bite-sized pieces.
Add the prawns, green beans, red pepper and pineapple chunks to the pan. Stir and simmer for about 2 minutes.
Add the rice noodles, pressing them down so they are submerged in the curry sauce.
Simmer for 3–4 minutes, stirring occasionally, until the noodles are tender and the prawns are cooked through.
Remove the lemongrass before serving and enjoy immediately.