How to Make It
Melt 1 tablespoon of the butter in a pot. Add the onion and garlic and cook over moderate heat until lightly browned, 4 minutes. Add the wine and bring to a boil. Simmer until reduced by half, 5 minutes. Add the kale and stock and bring to a boil. Cover partially and simmer over low heat until the kale is almost tender, 10 minutes. Add 1 1/2 tablespoons of the soy sauce with the sesame oil and sweet potato. Simmer uncovered until the potato is tender, 10 minutes longer.
Meanwhile, in a medium bowl, toss the pork with the lemon juice, sugar and the remaining 1 1/2 tablespoons of soy sauce. Let stand for 10 minutes.
Melt the remaining 1 tablespoon of butter in a large skillet. Add the pork and cook over high heat until browned and cooked through, about 10 minutes. Add the pork to the soup.
Heat the olive oil in a medium skillet until shimmering. Add the crumbled rice cakes and cook, stirring, until lightly toasted, about 2 minutes. Ladle the soup into bowls, spoon the sizzling rice on top and serve right away.