Heat the oil in a large saucepan over medium heat. Add the onion, season with salt, and cook, stirring occasionally, until softened, about 5 minutes.Add the chili paste, stir to combine, and cook until fragrant, about 1 minute. Add the cabbage and stir. Add the broth and tamari and bring to a boil. Taste and season with salt.Using a large serving spoon, add the tofu by very large spoonfuls, taking care not to break up the tofu into little bits. Gently press down on the tofu with the back of the spoon so that the broth is mostly covering it. Simmer until the tofu is heated through and the flavors have melded, about 3 minutes.Crack the eggs, if using, into the simmering mixture. Cover and simmer two more minutes.Divide rice and kimchi into 4 bowls, add broth and garnish with sliced scallions.