Cut the tempeh into equal cubes. Rinse the bok choy, drain it well, and slice the vegetable into fine strips. Peel the piece of ginger and grate it finely.
Heat the coconut oil in a wok or large skillet over medium-high heat. Add the tempeh cubes and sauté until they are golden brown on all sides in a few minutes. Then add the grated ginger and finely sliced bok choy to the pan. Stir-fry everything for three to four minutes, until the bok choy has wilted slightly but still feels firm.
Deglaze the hot dish with the tamari. Stir everything well so the liquid distributes evenly over the tempeh and vegetables. Scatter the raw cashews into the pan and toss them briefly to warm them.
Remove the pan from the heat. Divide the stir-fry directly onto plates and serve warm.