Bring a medium saucepot of water to a boil. Add the onion, daikon radish, and kombu. Cook until the kombu has expanded, around 5 minutes. Then, remove the broth from the saucepan.
Using the same saucepan, add the oil and saute the red pepper powder on low-medium heat. Keep an eye on this as red pepper powder can burn easily. Stir for 1 to 2 minutes.
Add and saute the mushroom, garlic, and kimchi for 2 to 3 minutes.
Lastly, add the soft tofu. You can slice these into large cubes as I did above, or toss the entire block into the saucepan and break with your spoon. Then, add the broth back and bring the saucepan to a boil. Top off with a freshly cracked egg, garnish with green onions, and serve immediately with rice.