In a large pot, oven medium high heat, melt butter with olive oil.
Add the onion. Cook the onion for 5-8 minutes or until the onion is soft and slightly brown but not caramelized.
Remove and set aside.
Stir in the beans, broth, salt, pepper, and red pepper flakes.
Bring to a boil and cook for 10 minutes.
Stir in the cabbage and reduce to a simmer.
Simmer for 20 minutes.
Stir in the vinegar and half the chopped dill.
Cook for 5 minus more.
Remove from what and serve.
Garnish with more fresh dill and a small dollop of sour cream.