Place beef in freezer for 15–20 minutes to firm up.
Slice beef thinly against the grain (⅛–¼ inch thick).
Whisk soy sauce, calamansi or lemon juice, brown sugar, oil, garlic, pepper, salt, and oyster sauce.
Place beef in shallow dish or zip-top bag.
Pour marinade over beef and coat evenly.
Cover or seal and refrigerate at least 4 hours or overnight.
Remove beef from marinade and let excess drip off.
Heat 1 tbsp oil in skillet over medium-high heat.
Cook beef in batches in a single layer.
Sear 2–3 minutes without moving until caramelized.
Flip and cook 1–2 minutes until cooked through.
Remove beef and keep warm.
Heat oil in separate pan for garlic rice.
Sauté garlic until golden and fragrant.
Add cooked rice and stir-fry 3–4 minutes.
Season rice with salt.
Fry eggs sunny-side up or over-easy.
Plate garlic rice, top with beef tapa and fried egg.
Serve with tomatoes and atchara if desired.