Slice your beef into thin slices against the grain. Add the beef slices to a large bowl, and combine with the soy sauce, vinegar, sugar, garlic, ground black pepper, and salt to taste. Gently mix to fully coat the beef. Cover, and let marinate for at least 1 hour.
Heat the oil on a pan over medium-high heat. Add in the marinated beef slices and fry for about 3-5 minutes on each side. The beef may begin to release lots of liquid initially, but continue cooking until all the liquid has been absorbed/evaporated. The tapa is finished when the beef is browned and slightly dried on the outside.
Serve the beef tapa tapsilog-style with sinangag (garlic fried rice), a fried egg, and fresh tomatoes and cucumbers on the side. Enjoy!
