In a small bowl, whisk together the soy sauce, vegetable oil, lime zest. Add in the light brown sugar, ginger, garlic and red pepper flake. Mix to combine. Season with salt and pepper to taste.
Pour the mixture over the prepared pulled pork and toss to coat.
In the same bowl, toss the cabbage, carrots and red pepper in lime juice.
To assemble the pork lettuce cups, add ¼ cup of pulled pork to each lettuce leaf. Top with the cabbage, carrot, and red pepper mixture. Sprinkle with cashews and serve immediately.