4 tablespoons extra-virgin olive oil, plus more for brushing the grill grates
Zest of 1 lemon plus 2 tablespoons juice
2 1/4 pounds boneless, skinless chicken breasts, cut into 1-inch pieces
Kosher salt and freshly ground black pepper
1/4 cup pine nuts
1 cup loosely packed fresh basil leaves
1 cup loosely packed fresh parsley leaves
1 clove garlic, crushed and peeled
1 large ripe avocado