Make the sauce. About 2 tsp of vegetable oil, 2 tsp of
garlic paste, 1 tbsp of cilantro stem, 2 tbsp of diced
red bell pepper. Stir them until fragrant. Toss in a tbsp of
oyster sauce, grind some
white pepper to taste, follow up with 1 tbsp of
soy sauce. Mix everything again. Now, this should smell amazing. Pour in the reserved mushroom soaking liquid. Bring it to a boil. Give it a taste to adjust the flavor. Mine needs 1/4 tsp of sugar and 1/8 tsp to balance the flavor. I also drizzled a little bit dark
soy sauce to change color. Turn the heat to low. Add some cornstarch water in batches. Just keep stirring until the sauce thickens up.