How to Make It
In a medium bowl, combine the onion with the cilantro, jalapeños, the 1/3 cup of lime juice and 1 tablespoon of the oil. Season with salt. Cover the pico de gallo and refrigerate for 1 hour.
Light a grill and oil the grate. Lightly brush the cut sides of the avocados with oil and lime juice; season with salt. Grill cut side down over high heat until charred, about 2 minutes. Transfer to a plate and let cool.
Scoop the avocado flesh into a large bowl and coarsely mash with a fork. Gently fold in 1 cup of the pico de gallo, the remaining 2 tablespoons of oil and the cumin and season generously with salt and pepper. Garnish with the remaining 1/3 cup of pico de gallo. Serve with tostones.