First, mince the loin and refrigerate.
Grate the carrots and celery, cut the celery and peppers into pieces or julienne.
Heat the oil in a pan and sauté the vegetables with the soup seasoning.
Add the minced meat and quickly fry until hot. Deglaze with soy sauce and season. Add a little water and let it boil down.
Roll up the puff pastry, spread the filling in the middle and fold tightly. Place on a baking tray and brush with egg. Cook in the oven at 180 °C for about 45 minutes on the middle shelf.
Meanwhile, prepare the herb sauce. Mix all ingredients in a bowl and season to taste. Season with garlic if necessary.
Arrange the meat strudel with the herb sauce and serve.