Begin by placing your beef in the freezer for 15-20 minutes at -5°C (23°F). This will make the meat easier to slice (para madaling mahiwa ang karne). While waiting, peel and mince one whole head of garlic (balatan at tadtarin ang isang buong ulo ng bawang).
Remove the meat from the freezer and slice it across the grain into thin pieces, approximately ¼ inch or 6mm thick. If desired, lightly score the surface of each slice with shallow cuts to help the marinade penetrate better.
In a large mixing bowl, combine ½ cup fish sauce (patis), ¾ cup brown sugar (asukal na pula), the minced garlic (tinadtad na bawang), and ½ teaspoon ground black pepper (dinurog na paminta). Mix well until the sugar completely dissolves (haluing mabuti hanggang matunaw ang asukal).
Add the sliced meat to the marinade and massage thoroughly to ensure each piece is well-coated. Cover the bowl and place in the refrigerator at 4°C (40°F) for 8 hours or overnight. Do not marinate longer than 24 hours to prevent the meat from becoming too salty (huwag ihalo ng sobra sa 24 oras para hindi masyadong maalat).
After marinating, remove the meat from the refrigerator and let it rest at room temperature for 15 minutes (panatilihin sa temperatura ng kapaligiran). While waiting, prepare your cooking pan by placing it over medium heat (katamtamang init) at 180°C (350°F).
Drain the meat from the marinade but do not discard the marinade. Arrange the meat pieces in a single layer in your heated pan. Add 1 cup of water (1 tasang tubig) and any remaining marinade. Reduce heat to achieve a gentle simmer at 165°C (330°F).
Allow the meat to simmer for 15-20 minutes or until the liquid is mostly absorbed and the meat becomes tender (pakuluan hanggang lumambot ang karne at matuyo ang sabaw). Watch carefully to prevent the liquid from drying out completely.
Once the liquid is mostly absorbed, add 2 tablespoons of cooking oil (mantika) and increase the heat to medium-high at 200°C (400°F). Cook the meat for 5-7 minutes, turning pieces occasionally, until they develop a deep brown color with caramelized edges (lutuin hanggang maging kulay brown at magkaroon ng magaspang na gilid).
The tapa is ready when it achieves a deep mahogany color with slightly crispy edges while remaining tender in the center (luto na ang tapa kapag maitim na brown ang kulay at magaspang ang gilid ngunit malambot sa gitna). You should see caramelized spots on the surface and smell a sweet-garlicky aroma.
To serve traditionally, pair with garlic fried rice (sinangag) and a sunny-side up egg (pritong itlog) to make the classic tapsilog. Serve with sliced tomatoes and cucumbers (kamatis at pipino) on the side, and prepare a dipping sauce of spiced vinegar (suka na may paminta) if desired.
For storage, let the tapa cool completely before transferring to an airtight container. Keep in the refrigerator at 4°C (40°F) for up to 3-4 days, or freeze at -18°C (0°F) for up to 3 months (maaaring itago sa freezer ng hanggang 3 buwan).
To reheat, warm a pan over medium heat at 180°C (350°F). Add the tapa and 2 tablespoons of water (tubig), cover the pan, and steam for 2-3 minutes. Remove the lid and continue cooking until the desired crispiness is achieved (hanggang maging magaspang ulit ang gilid).