Wash and dry the duck fillet. Cut in the middle into two parts, cut the skin diagonally to the meat.
Prepare the marinade. Mix soy sauce with mustard, honey and lemon juice.
Put the duck fillet in the marinade. Season with salt and pepper. Leave to marinate for 1.5-2 hours. Then remove the fillets from the marinade and fry in a dry pan for a couple of minutes on both sides. First fry the side with the skin.
Transfer the duck to a baking dish and send it to the oven, preheated to 200 *, for 10 minutes in convection mode.
Transfer the duck fillet to a platter.
Cover tightly with a deep plate on top, let the fillet "rest" for 10 minutes. During this time, juice will be released from it.
Pour the remaining marinade into a saucepan, add 1 tablespoon of lemon juice (if necessary), 15 g of butter and evaporate over medium heat until the sauce thickens.
Strain the sauce and cool it.
Defrost the beans. Boil in salted water for 5-7 minutes.
Flip into a colander and cool.
Slice the fillet obliquely and place on a platter along with arugula, frieze salad and boiled string beans.
Pour the sauce over the duck. Serve with olive oil (for greens).