For satay sauce, process cashew nuts in a food processor until finely ground, then add almond butter, ginger and fresh chilli, and process to a coarse paste. Add tamari, sesame oil and maple syrup, blend well, then, with the motor running, slowly add 60ml water and process until smooth. Add a little more water if you prefer a thinner sauce. Set aside in a bowl.
Heat a barbecue or char-grill pan over high heat. Combine tamari, coconut oil, ginger, garlic, chilli flakes and cumin in a large bowl. Add prawns, toss to coat well and set aside to marinate (10 minutes).
Grill prawns, turning once, until charred, golden-brown and cooked through (1½-2 minutes each side). Season to taste and serve hot with satay sauce scattered with extra chopped cashew nuts.