Add the brown sugar, garlic cloves, green onions, ginger, and hot pepper to a clean quart sized jar. Pour the boiling water over the top and swirl to dissolve the sugar and release the aroma from the aromatics. Pour in the soy sauce and rice vinegar. Swirl gently. Plunk the eggs into the mixture, pressing gently to make sure they're all submerged. Lid tightly, invert the jar a couple of times, and stash in the refrigerator. They can be used as soon as 2 hours after soaking, but can be left up to 24 hours in the mixture to enhance and deepen the soy sauce flavour.
Serve cold, room temperature, or heated up, alone with a little sprinkling of togarashi or black pepper, or over rice, congee/juk, ramen, salad, or any other place you think an umami-packed, fragrant, soy sauce flavoured egg would be welcome.