Gently fry the onion in the oil in a heavy bottom pan over a low to medium heat for 5 minutes until translucent and browning at the edges. Add the garlic, red peppers, ginger and chilli and fry for a further 2 minutes.
Add the massaman paste, stir well and cook for 1 minute.
Add the fish sauce, stir to combine and cook for 1 minute.
Add the strips of meat, stir well to coat the meat and fry gently until the meat softens and absorbs some colour.
Add the water chesnuts and bamboo shoots and cook for a further 2 minutes until heated through.
Add the coconut milk, mix well, cover and simmer gently for 15 minutes.
Remove the lid and raise the heat to reduce the liquid until a creamy consistency.
Squeeze over the juice of a lime and serve.