Start by cleaning your squid if not already done. Slice the squid into rings or leave them whole for a more dramatic presentation. Prepare your garlic, onion, chilies, and scallions as indicated in the ingredient list.
In a wok or large skillet, heat 2 tablespoons of oil over medium-high heat until shimmering. This should take about 1-2 minutes.
Add the thinly sliced garlic to the hot oil and sauté for about 30 seconds until fragrant. Be careful not to let it burn.
Add in the pieces of yellow onion and red chilies. Stir-fry for about 2 minutes until the onion becomes translucent and the chilies soften.
Add the cleaned squid to the pan. Stir-fry for about 2-3 minutes until the squid turns opaque and slightly curled.
Stir in the mashed fermented black beans, scallions, soy sauce, oyster sauce, dark soy sauce, and optional sugar. Mix well to ensure the squid is evenly coated.
In a small bowl, mix the cornstarch with 2 tablespoons of water to create a slurry. Pour this into the skillet and stir quickly to thicken the sauce, cooking for an additional minute.
Drizzle in the sesame oil for that nutty flavor. Mix well and remove from heat.
Serve your Squid with Black Bean Sauce hot, garnished with additional scallions if desired.
