Preheat oven to 375 degrees F. Take your napa cabbage half, and cut it in half again lengthwise. Place the cabbage on a sheet pan and drizzle lightly with oil. Roast for 25 minutes.
Meanwhile, in a large stockpot, heat 1 tablespoon oil over medium heat. Add the ginger and garlic and cook for 2 minutes, until fragrant but not browned. Add the fermented bean curd and cook for another minute. Then add the onion, carrots, scallions, daikon, kelp, dried shiitake mushrooms, and water. When the napa cabbage is done roasting, add it to the pot as well.
Bring to a boil, turn the heat down to low, and simmer with the lid on for 4 hours. Strain the stock, and season with salt to taste.
This stock can be stored in containers (leave enough room in the container for the liquid to expand as it freezes) and frozen for up to 6 months. If not freezing, use within 3-4 days.
Asian Vegetable Stock by The Woks of Life. Recipe URL: https://thewoksoflife.com/asian-vegetable-stock/