Whisk egg and water in a shallow dish.

Coat pork cutlets in the egg mixture.

Combine cornflake crumbs, garlic powder, sesame seeds, salt, and pepper on parchment paper.

Coat each cutlet in the cornflake mixture, pressing to adhere.

Heat oil in a large skillet over medium-high heat.

Fry cutlets until golden brown on both sides.

Drain on paper towels.

Sauté leeks with salt in a small pot.

Add mushrooms and cook for 1-2 minutes.

Stir in flour and cook for 1 minute.

Gradually add cream, stirring constantly.

Add mustard, pepper, and salt to taste.

Simmer for 5-8 minutes, do not boil.

Divide sauce among the cutlets and serve.