How to Make It
In a large pot, melt the butter over moderately low heat. Add the onion and cook, stirring occasionally, until starting to soften, about 3 minutes. Stir in the minced ginger and the cabbage and cook for 1 minute longer.
Add the broth, potatoes, smashed ginger, and 1 teaspoon of the salt. Bring to a boil. Reduce the heat and simmer until the potatoes are tender, about 10 minutes.
Stir in the pork and the remaining 1 teaspoon salt. Cook until the pork is just done, about 3 minutes. Stir in the lemon juice and parsley. Remove the pieces of smashed ginger before serving.
You'll want to use really fresh ginger here; it's integral to the flavoring of the soup. Look for a piece that has taut skin and is firm to the touch. After the ginger is peeled (the easiest way is to scrape the peel off with a spoon), its color should be pale yellow. If the ginger is blueish green instead, chances are the piece is old and won't have the vibrant flavor you're looking for.