Toast the coconut in a dry frying pan over medium heat for a couple of minutes until it smells fragrant and turns golden brown, then set aside immediately to prevent burning.

Sizzle the mustard seeds in oil until they begin to pop, then add the shallots and fry for about 8 minutes until they are soft and starting to caramelize.

Add the cashews to the shallots and fry until they are golden and toasted, then remove the pan from the heat while you prepare the beans.

Boil the green beans for about 4 minutes until they are tender but still have a snappy bite, then drain them well.

Return the shallot and cashew mixture to high heat, toss in the beans, tamarind, chile, and salt, and stir-fry until sizzling before folding in the toasted coconut.