Lemongrass Chicken Lettuce Wraps

Name: Lemongrass Chicken Lettuce Wraps
Ingredients: 9 ounces ground chicken; 1 handfull lemongrass; 1 teaspoon rice wine vinegar; 2-3 cloves garlic; 1 1-inch piece of ginger, sliced thin; 1 medium-sized onion, sliced; 1 medium-sized tomato, chopped; 1 bell pepper, chopped; 1/4 cup roasted cashewnuts or peanuts; 1/4 cup sliced mushrooms of your choice; 2 tablespoons soy sauce; 1 teaspoon sugar; 1 teaspoon red chilli flakes OR 1 small red or green chilli, chopped; 1 tablespoon sesame oil; salt to taste; 6-8 iceberg lettuce leaves, washed and dried; 1 1/2 cups water for boiling