Marinade the chicken thigh for 30 minutes and pan fry until medium done.
Wash the yam and steam for 5 minutes. Remove the peel, cut into sections and then let cool and set aside.
Heat the oil over medium heat, saute the ginger, garlic and purple onion until fragrant.
Add in chicken thigh, mushroom and yam, and stir fry. Add in seasonings and hot water, then mix well and cover the lid. Cook with low heat for 15 minutes or until the chicken thigh is well done.