Begin by gently draining the excess water from the silken tofu. Carefully slice the tofu into pieces about ½ to 1 inch thick, ensuring you use a sharp knife to maintain the tofu's integrity. Set it aside on a heat-proof dish that can fit into your steamer or pot, ready for steaming.

In a mixing bowl, combine the minced garlic, soy sauce, black vinegar, sesame oil, vegetarian oyster sauce, sugar, and optional chili oil. Stir thoroughly until the sugar is dissolved and the ingredients are well blended.

Prepare your steamer by filling the bottom with water, ensuring it does not touch the dish of tofu. Bring the water to a gentle boil.

Once the water is boiling, carefully place the dish with tofu into the steamer or saucepan. Cover with a lid and steam for about 8 to 10 minutes, or until the tofu is warmed through and slightly firm to the touch.

After steaming, carefully lift the dish out of the steamer (it will be hot). Drain any excess liquid from the tofu, then pour the prepared soy garlic sauce over the tofu evenly. Garnish with freshly chopped spring onions and coriander for a burst of color and flavor.