Whisk the hoisin sauce, rice vinegar, maple syrup, soy sauce, water, cornstarch, garlic, ginger and white pepper together in a small bowl.
Coat the bottom of a large skillet with 1 tablespoon of oil and place it over medium heat.
Once the oil is hot, add the tempeh cubes in an even layer. Cook the tempeh for about 10 minutes, flipping halfway through, until the pieces are lightly browned.
Remove the tempeh from the skillet and transfer it to a plate.
Coat the skillet with the remaining tablespoon of oil and raise the heat to high. Add the bell pepper and white parts of scallions. Stir-fry until the peppers are tender-crisp, about 3 minutes.
Return the tempeh to the skillet, then add the hoisin sauce mixture and cashews. Flip everything a few times with a spatula to distribute the ingredients.
Continue cooking the mixture, flipping it frequently, until the sauce thickens a bit and coats the tempeh and peppers.
Remove the skillet from heat.
Serve the stir-fry with rice and top it with sesame seeds and the green parts of your scallions.
Nutrition information does not include accompaniments.