For the pork tenderloin sweet and sour, cut the meat into very narrow slices. Clean the leeks, cut lengthwise, wash carefully and cut into narrow rings. Defrost the peas. Drain pineapple and cut into bite-sized pieces.
Heat a little oil, sauté leeks. Add meat and fry briefly. Add peas and pineapple, stir several times and remove everything from the pan.
Dissolve and boil away the drippings with a little water and pineapple juice, add the remaining ingredients and stir. Season vigorously and let the roasted ingredients infuse in it but do not boil anymore. Season to taste and serve the pork tenderloin sweet and sour.