Holding the knife at a 45-degree angle, cut the chicken fillets into slices about a quarter of an inch thick.
In a mixing bowl, whisk together the egg white, fish sauce, lemongrass, rice wine and two tablespoons of starch. Add the chicken and mix well. Cover and marinate in the fridge for at least an hour (overnight works best).
Heat the cooking oil in a wok or frying pan.
Separate the chicken pieces and toss each one in starch.
Over high heat, fry the chicken pieces in batches until lightly browned and crisp. If the chicken slices are thin enough, each batch should cook in no more than two to three minutes. Scoop out the chicken and drain on a stack of paper towels.
Pour off the oil leaving only about a tablespoonful. Reheat the oil and saute the garlic, ginger, chilies and shallots. Add the carrot slices and pineapple chunks. Stir fry for a minute.
Put the chicken back into the pan.
Pour in the sweet and sour sauce (recipe below). Toss everything together until everything is coated with the sauce.
Serve at once.