This is a versatile sauce - add it to mayo for a sandwich spread; marinate chicken, fish, or tofu; mix it into couscous; or drizzle it over scrambled eggs and toast. It is subtly spicy and the acid is nicely tempered by the savoury cumin. I used cilantro, but you can also substitute half with parsley. This recipe comes from Samin Nosrat's Salt Fat Acid Heat, a cookbook I highly recommend.
Begin by toasting the cumin seeds in a dry cast iron pan for a few minutes, until the aroma is released and the seeds start to pop. Pour the seeds into a mortar and grind with a pinch of salt.
Add all ingredients into a food processor or blender and pulse until there are no chunks. Taste and add more salt or lime juice, according to taste. Refrigerate until serving.