Kosher salt and freshly ground black pepper, to taste
Tortilla chips, for serving
Directions
Heat a cast-iron skillet over high heat. Working in batches, sear the plum tomatoes, jalapeños, garlic and onion until charred all over, 5 minutes for the tomatoes and garlic, and 8 minutes for the jalapeños and onion.
Transfer all the charred vegetables to the bowl of a food processor and let cool completely. Add the cilantro, lime juice and agave, then pulse until a chunky purée forms. Season with salt and pepper, then transfer to a bowl. Serve with tortilla chips.