Curry Sauce from Bliss

This was a great vegan Curry Sauce from the Williamsburg cafe, Bliss.
Simmer:
2c. Onion
1Tbsp. + 1tsp. each:
Cumin, Tumeric, Coriander, Chili Powder
6 cloves garlic, minced
2" ginger
1/2 stalk Lemongrass

Simmer 5-10 min. then Add:
1 lemon-zest only
1/4 tsp. each, salt and pepper

Simmer---> add water if needed.
Add:
2 1/4 can coconut milk
Boil over medium/high heat then puree-removing lemongrass.