Place all of the sesame ginger sauce ingredients into a small bowl and whisk until combined.
Heat a large skillet over medium heat and add the olive oil. When the oil is hot, add the carrot, red pepper and peas. Cook for 3 minutes, stirring occasionally, and then add the crumbled tempeh.
Continue to cook for another 3 minutes and then pour in the sauce. Stir until everything is combined and cook until sauce is thickened, 7-10 minutes.
Let the mixture cool for a few minutes (to avoid wilting the lettuce), and then spoon the mixture into lettuce cups. Garnish with cashews and green onions, if desired.
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