Peel potatoes and carrots into 1/2 inch pieces. Put in large sauce pan and fill with water until vegtables are just covered. Bring to boil, then simmer for 15-20 minutes or until vegtables are tender. Remove from heat, drain, and set aside.
Puree onions, ginger, garlic, and peppers in food processor. Pour oil in large sauce pan and put on medium heat. Add onion puree and sautee for five minutes, or until onions no longer smell raw. Add water, salt, pepper, cardamom, and cooked vegtables. Stir well and simmer for 15 minutes.