Prepare all ingredients: slice the yam, peel and devein the shrimp, leaving the back open.
Briefly blanch the yam and shrimp until about 80% cooked. Remove and drain.
Heat oil in a wok over low heat. Sauté garlic and ginger until fragrant. Add XO sauce and stir-fry until fragrant. Pan-fry the shiitake mushrooms until fragrant.
Increase heat to medium-high, add oyster sauce and shiitake mushrooms, stir-fry until combined. Add a little water.
Add chicken powder, white pepper, and sugar to taste. Add red, yellow, and green bell peppers, yam, and shrimp. Stir-fry until heated through.
Reduce heat to low, add cornstarch slurry to thicken the sauce. Drizzle with Shaoxing Huadiao and stir-fry until well combined. Serve hot.