Prepare mushrooms, chilies, and other ingredients.

Remove stems from king oyster and shiitake mushrooms, then cut them into bite-sized pieces.

Slice green peppers in half, remove seeds, and chop finely.

Deseed green and red chilies, then chop finely. Add more green chilies for extra spice if desired.

Mix soy sauce, oyster sauce, ketchup, vinegar, sugar, and sesame oil to create the sauce.

Combine frying flour, eggs, and water to make the batter.

Coat mushrooms evenly with the batter.

Heat vegetable oil in a pan over medium heat and fry mushrooms for about 2 minutes.

In a separate pan, heat a small amount of oil and sauté minced garlic and chopped chilies over medium heat.

Add fried mushrooms to the pan, pour in the sauce, and stir-fry until evenly coated.