Tender Sliced Beef for Lunch Box

Cut the tender beef into thin strips.

Season the beef strips with your preferred seasonings and add soy sauce, allowing them to marinate for a few minutes to absorb the flavor.

Heat the oil thoroughly in a skillet. Brown the beef strips in small batches to prevent the temperature from dropping, which would cause the meat to steam (and become tough).

Quickly brown both sides of each batch of beef so that it doesn't dry out.

Remove the browned beef from the skillet and set aside.

In the same skillet, add the thinly sliced onion and sauté.

To create a creamy sauce, mix one tablespoon of flour with a little water until dissolved, forming a thin paste.

Pour the reserved liquid mixture into the skillet with the onions and stir quickly. Do not let it cook for too long.

Return the beef to the skillet with the sauce and toss quickly to coat everything before serving.