In a bowl, combine the soy sauce, calamansi juice, and minced garlic to make the marinade.
Marinate the thinly sliced beef in the mixture for at least 30 minutes.
Heat the cooking oil in a pan over medium heat.
Fry the marinated beef slices until browned on both sides. Set aside.
In the same pan, sauté the sliced onions until translucent.
Add the fried beef back into the pan with the onions.
Pour the remaining marinade over the beef and onions. Simmer for a few minutes until the beef is tender.
Season with salt and pepper to taste.
Serve hot with steamed rice and garnish with fried garlic or toasted sesame seeds if desired.
Enjoy!
