Soak the sotanghon and wood ear mushrooms in hot water in separate bowls.
Stir the annatto powder and oil, and pour into a sauce pan, and turn on the heat.
Lay the chicken fillets, skin side down, in the oil and cook medium-high heat for a minute or two to render fat from the skin. Flip and cook for another minute.
Pour in the broth. Season with fish sauce and pepper.
Bring to the boil.
Dump the cabbage and carrot into the pan.
Drain the sotanghon and add to the vegetables in the pan.
Drain the wood ear mushrooms, trim, slice and add to the sotanghon and vegetables.
Simmer everything together for five minutes.
Taste the broth and add more patis, if needed.
Scoop out the chicken and move to a cutting board.
Cut the chicken into strips and put back in the pan.
Simmer the chicken sotanghon soup for another five to seven minutes.
To serve, ladle the chicken sotanghon soup into bowls and sprinkle with sliced scallions and fried garlic.