In a large bowl, combine the avocados, onion, jalapeño, cilantro, lime juice, salt, and pepper. Stir well. Serve with the tortilla chips.Tip: Plan ahead. You can prepare guacamole up to two hours before serving. To keep it from turning brown, cover the bowl with plastic wrap so that the wrap lies directly on the guacamole, with no air in between, then refrigerate.