Cut chicken or tofu into long strips ( if grilling) or bite sized pieces if cooking in a skillet or grill pan.
To prepare the marinade place lemongrass in a food processor and pulse until very finely chopped. Add the remaining ingredients: onion, garlic, salt, sugar, five spice and pulse until finely chopped. Place mixture in a bowl, stir in oil and chicken. Let marinate 30 minutes or up to 24 hours.
Boil noodles per package directions, usually boil for 2-3 minutes. Drain and rinse with cold water. ( Note: If you prefer noodles warm, rinse with hot water).
Prep the vegetables as listed.
To prepare the dressing mix lime juice, fish sauce, water, sugar and chilies in a small bowl. Set aside.
Preheat grill. Grill chicken (or tofu or shrimp) and cook on medium heat until cooked through. Note: Can use a grill pan or skillet stovetop.
To assemble bowls place noodles, vegetables, fresh herbs, grilled chicken (or shrimp or tofu), grouped together in a bowl. Spoon a little dressing over the noodles and veggies.