Place onion, garlic & ginger in blender and form into smooth paste. Saute this paste in oil 5 minutes. Add turmeric, coriander, cumin and chili powder. Simmer 4 minutes. Add tomatoes, simmer 2 minutes. Add chicken, cook 5 minutes. Add salt & water, boil, cover & simmer 20 minutes. Add peppers, garam masala, cook covered 5 minutes. Garnish with cilantor if desired.