First, prepare the chicken. Cut the fillet in half lengthwise, but do not cut it all the way through, then open it like a book. Grease with soy sauce. Rub with salt and pepper.
Prepare the batter for the chicken. Break the egg into a separate bowl and beat it with a fork or whisk. Dip the chicken fillet into the egg.
Roll the chicken fillet in breadcrumbs on all sides. Heat a frying pan with vegetable oil and fry the fillet for 7-9 minutes on both sides until golden brown.
Cut tomatoes and cucumbers into thin slices.
Prepare the sauce. Finely chop the dill and garlic. Mix the mayonnaise, dill and garlic in a bowl. Spread the sauce on one piece of bread.
Assemble the sandwich: place a lettuce leaf on top of the sauce, then the chicken fillet cut into slices, tomato, lettuce leaf again and sauce. Then heat the frying pan with vegetable oil and fry the sandwich for 2 minutes on each side until crisp.