1. In a medium skillet, heat the olive oil until shimmering. Add the pistachios and cook, stirring, until lightly toasted, about 3 minutes.
2. Using a slotted spoon, transfer the pistachios to paper towels to drain; reserve the oil in the skillet. Season the pistachios with salt.
3. Scoop the avocados into a medium bowl and coarsely mash with a fork. Stir in the onion, jalapeños, lime juice, 1/2 cup of cilantro and all but 2 tablespoons of the pistachios; season with salt.
4. Scrape the guacamole into a serving bowl and drizzle some of the reserved oil on top.
5. Garnish with chopped cilantro and the remaining 2 tablespoons of pistachios and serve with tortilla chips.