Saute onion and jalapeno in olive oil and butter for about 5 minutes until softened.
Add garlic, ginger, cumin, coriander seed, turmeric, and curry powder. Saute 2-3 minutes more.
Add tomato, spinach, beans, water and salt. Bring to a simmer and partially cover. Simmer for about 20 minutes.
Combine milk and sour cream until sour cream is dissolved. Temper with some liquid from the pan and then stir into pan. Add garam masala. Simmer a few minutes more. Garnish with chopped fresh coriander.