Make the bola-bola: In a bowl, mix ground pork, garlic, onion, beaten egg, and cornstarch. Season with salt, pepper, and fish sauce. Chill for 15 minutes for easier handling, then form into small balls. Fry in a saucepan over medium-high heat until browned and cooked through. Set aside.
Make the scrambled eggs: Heat a small amount of oil in a skillet over medium heat. Pour in the eggs and let them cook undisturbed until they begin to set around the edges. Tilt the pan as needed to spread the egg mixture out thinly across the surface. Once the egg is mostly set, you can gently flip it over to cook the other side briefly. Transfer to a plate and slice it into thin strips. Set aside.
Soak the sotanghon: Soak the noodles in warm water for about 10 minutes or as directed on the package, until soft but not fully cooked. Avoid over-soaking, as they'll continue to cook in the pan. Once ready, drain and set aside.
Prepare the liquid mixture: In a bowl, mix the chicken base, annatto powder, fish sauce, soy sauce, and oyster sauce with 1 cup of hot water to dissolve the annatto. Mix well and set aside.Prepare another 1 to 2 cups of hot water; you’ll need more or less depending on the noodles you're using. Cook and shred chicken: Season both sides of the chicken with salt and pepper. For quick and even cooking, flatten the pieces by slicing them open. In a wok or pan, sear over medium-high heat until browned and fully cooked. Let them cool, then shred and set aside.
Sauté aromatics and mushrooms: If necessary, add a bit more oil to the pan and sauté garlic and onions until softened. Add the shiitake mushrooms and continue sautéing until nicely browned. Then, add the wood ear mushrooms and sauté them briefly with the rest.
Add the vegetables: Add the carrots, snow peas, and celery, then stir-fry until just cooked but still crisp. Then, add the cabbage and keep tossing just until the cabbage slightly wilts. Season the vegetables with salt and pepper.
Add the chicken: Add the shredded chicken and toss it together with the vegetables until thoroughly heated.
Add the noodles and liquid: Add the sotanghon and prepared liquid mixture. Turn up the heat to keep everything hot and cooking well after the noodles are added.
Toss the noodles: Use two wooden spoons and toss everything together to evenly coat the noodles and distribute the ingredients. If it starts to look a bit dry, gradually pour in the extra hot water you prepared earlier. The amount you'll need will vary based on the type of noodles you're using, so keep adding until they're just right. Season with ground pepper and tweak any other seasonings as needed. Turn off the heat once everything's perfect. Serve: Top your Sotanghon Guisado with bola bola, thinly sliced scrambled eggs, sliced scallions, and calamansi or lemon as desired.