In a large pot or preferably pressure cooker, heat oil over high heat until shimmering. Add beef pieces and sear on all sides.
Once beef bones are seared, add in the onions and cook until fragrant.
Once fragrant, add in water, enough to completely submerge the beef pieces. Allow to boil. Once boiling, turn heat to low and allow to simmer, covered for one hour.
After cooking for one hour, scoop out any scum or debris which float to the top. Add in the cabbage and bok choy pieces, peppercorns, and season to taste with salt and pepper. Cover again and cook, simmering gently for another 3 hours.
After 3 hours, remove any solids that have floated to the top. Add in the patis and stir to combine.
Once ready to serve, transfer the bulalo into a large bowl and serve with freshly steamed rice and your dipping sauce of choice.