Heat oil in pan over medium heat.
Add onions, ginger, and garlic, and cook until thin and translucent (about 2 minutes).
Add turmeric powder and cook for 1 additional minute.
Add tomatoes and cook for 3 additional minutes.
Bring curry to boil and let simmer on medium heat for 5 minutes.
Garnish with chopped cilantro and serve with cooked basmati rice.