Cube the sweet potatoes and place on a baking sheet. Spray with cooking spray and shake on some salt and pepper to taste.
Bake for 20 to 25 minutes. Place under the broiler for 2 to 3 additional minutes to make the sweet potatoes crispy.
Meanwhile, add the cilantro, pistachios, jalapeño, garlic, lime juice, lime zest, olive oil, water, salt, and cumin to a food processor. Blend until smooth.
When sweet potatoes are done, put on a serving plate and dollop on the cilantro pesto. Serve!