Start by preheating your oven to 160°C (320°F). Take your pork and rub baking soda all over the skin, then season the entire piece generously with salt and pepper. Place it on a roasting rack with a dripping tray underneath.
Roast the pork for 2 hours at 160°C. After this time, increase the temperature to 180°C (356°F) and continue roasting for another 45-60 minutes until the skin turns golden brown and crispy.
While the pork is roasting, prepare your vegetables. Slice your cabbage, onions, and carrots. Mince your garlic, ginger, and chilies. Chop the Chinese celery and set everything aside.
Once the pork is done, let it cool until you can handle it. Chop it into very small pieces, about the size of a dice. Place the chopped pork in a bowl and mix it with ¼ cup of calamansi juice, soy sauce, diced onion, and chilies. Add a pinch of salt and mix well.
Now soak your bihon noodles in room temperature water, but no longer than 10 minutes. While the noodles are soaking, start heating your wok over medium heat with a bit of oil.
Add garlic and onions to your hot wok and cook until they smell fragrant. Pour in the chicken broth and add all your prepared vegetables. Let this come to a boil.
Drain your noodles and add them to the boiling mixture along with the soy sauce. Stir-fry everything together for 5 minutes, gently tossing to combine. Season with fish sauce and black pepper to your taste. Remove the noodles from the wok and set aside.
Clean your wok and place it back over high heat with a little oil. Once the oil is smoking hot, add your seasoned chopped pork mixture along with the garlic, onions, and ginger. Let it sizzle and get crispy on the bottom.
Turn off the heat and drizzle the remaining calamansi juice over the pork. Quickly crack in the eggs and stir everything together – the residual heat will cook the eggs just enough.
To serve, place your cooked pancit on a large platter and top it with the hot sisig. Sprinkle chopped coriander over everything and arrange calamansi or lemon wedges around the plate. Serve right away while the sisig is still sizzling.