Dubu kimchi is a pub dish, the sort of thing that lands on the table with a bottle of soju in every Korean drinking house. Sour kimchi and pork belly are fried hard together until the kimchi caramelises, then spooned beside slices of plain warm tofu.
The contrast is the whole point. The tofu is soft, mild and quietly high in protein, and it takes the edge off kimchi that has been cooked until it is punchy and sweet. Older, more sour kimchi is better here than fresh.