Begin by rinsing the fermented black beans thoroughly under cool running water to remove excess saltiness. Chop them roughly, leaving some pieces larger for texture; mash half of the beans with a fork to create a paste.

In a small saucepan, heat 2 tablespoons of vegetable oil over low heat. Once the oil is shimmering, add the minced garlic and shallot, sautéing gently for about 5 minutes until fragrant.

Stir the prepared fermented beans and 1 tablespoon of brown sugar into the saucepan, mixing until combined. Allow to cook for 2 minutes over low heat.

Pour in 2 tablespoons of Shaoxing wine, along with 1/4 cup of soy sauce and 1/2 cup of broth mixed with 1 teaspoon of cornstarch. Stir to combine, then cover and simmer for 7 minutes.

Remove the lid and continue cooking for an additional 3 minutes, stirring frequently to ensure it doesn't stick. Adjust thickness by adding broth if necessary.

Once the sauce reaches desired thickness, remove from heat and let cool to room temperature. Transfer it into an airtight container.