In a nonstick Dutch oven, saute the celery, onions, leeks, green pepper, jalapenos and garlic in oil until tender. Add the potatoes, broth, water, pepper and salt. Bring to a boil. Reduce heat; cover and simmer for 10-15 minutes or until potatoes are tender, stirring occasionally.
Combine flour and milk until smooth; stir into soup. Cook and stir for 2 minutes or until thickened and bubbly. Reduce heat to low. Stir in sour cream and green onions until blended; heat through (do not boil).