This dish is best with kimchi that's well fermented and quite tangy. Serve with rice or rice noodles if you like.
Heat vegetable oil in a medium pot over medium-high heat. Add pork and cook until starting to brown, about 3 minutes. Add onion, garlic, and ginger and cook until onion begins to soften, about 2 minutes. Add broth, cover, and boil until pork is tender, 7 to 10 minutes.
Add kimchi, jalapeño, sesame oil, soy sauce, and sesame seeds; cover and return to a boil. Season to taste with salt and pepper. Add tofu and half the green onions and cook until heated through. Ladle into bowls and sprinkle with remaining green onions.
*Find in the Asian aisle of most grocery stores or refrigerated in the produce section.