Add cilantro leaves, jalapeno, and lime juice to a food processor. Blend on low until finely chopped, scraping down the sides with a rubber spatula as needed.
Add vegan sour cream, kosher salt, and onion powder. Pulse again until well combined.
Notes
This recipe makes 1 cup and a serving is about 2 tablespoons. If you want to use more sauce (I regularly do) or are feeding more people, double the recipe.