First make the anchovy stock. Place the trimmed anchovies, radish slices, kelp, and shiitake mushrooms in a medium pot with 5 cups of water. Bring the water to a boil. Once the stock is boiling, turn the heat down to medium-low and simmer for 25 minutes.
After 25 minutes, strain the stock. Save the mushrooms and slice thinly to put into your soondubu.
Now you’re ready to assemble the soondubu. Heat a small pot or your handy dandy earthenware Korean stew pot over medium-high heat. It takes a few minutes for the earthenware pot to get hot--don’t rush it, as there’s a chance it could crack if heated too quickly.
Add the oil to the pot, followed by the garlic and onions. (Note, if you’re cooking these two servings in two separate individual-serving pots, you’ll have to split all the ingredients down the middle for each.)
Stir fry until the onions are translucent. Turn the heat up to high, and add the pork belly. Let brown and caramelize. Add the kimchi, sliced mushrooms and stir to combine.
Add about 1 1/3 cups of the anchovy stock (or 2/3 cup each for the individual pots), followed by the salt, sugar, Korean chili flakes, and sesame oil. Stir to combine.
Next, add the tofu, about a quarter of a standard block or half of a tube (if you are using a Korean brand that comes in cylindrical form). Break up the tofu lightly into large chunks. Bring the soondubu to a boil.
Crack an egg over the top of each pot, and cook for 1 minute. Top with the scallions and serve with white rice and some additional kimchi on the side.