This sauce is classic Mexican food. It is made of ground green tomatoes with onions, garlic, cilantro, chili, salt and pepper to taste. You can put these ingredients to roast and grind in pestle, or grind in blender, cook and season the sauce.
It is used to prepare traditional Mexican foods such as enchiladas or pork in green sauce. Or, more zesty snacks like tacos, quesadillas, etc.