In a large non-reactive bowl, combine the soy sauce, calamansi juice, minced garlic, sugar, salt, and pepper. Stir well until the sugar and salt are completely dissolved, forming a balanced marinade.

Add the thinly sliced beef sirloin to the bowl, ensuring each piece is well coated in the mixture. Massage the marinade gently into the meat for even absorption. Cover the bowl and refrigerate overnight to allow the flavors to fully penetrate the beef.

When ready to cook, remove the beef from the refrigerator and drain any excess marinade. Heat about one tablespoon of canola oil in a wide skillet over medium heat.

Arrange the beef slices in a single layer and cook for 3 to 5 minutes, turning occasionally. The meat will release some liquid as it cooks; continue cooking until most of the liquid has evaporated.

Add another tablespoon of oil to the pan and continue to cook until the beef begins to caramelize and turn lightly golden on the edges. This step enhances the flavor and gives the tapa its signature texture and color.

Once cooked, remove the beef from the pan and cut it into serving portions. Serve hot, traditionally paired with garlic fried rice and fried eggs for a classic Filipino breakfast known as tapsilog.