Afghani Korma Sauce - cooking recipe

Ingredients

1 onion
3 cups water
1 (16 ounce) can tomato sauce
1 teaspoon salt
1 1/2 teaspoons ground coriander
1 tablespoon vegetable oil
1/4 teaspoon fresh ground black pepper

Preparation

Slice onions very thin and boil in water until tender, about 15 minutes; drain water and put onions in a blender.
Add oil, tomato sauce, salt, pepper, coriander and process until smooth; place sauce into a saucepan and bring to a boil.
Turn heat down to low and simmer until thickened.