To prepare the pesto, add the basil to a food processor along with the garlic, lemon zest, pine nuts, Parmesan and sundried tomatoes. Blend to form a chunky paste.
Add four tablespoons of olive oil and season to taste. Blend until you have a pesto sauce.
Slice the mushrooms into wedges about 1/2 inch thick. Add to a mixing bowl with the lemon juice.
Add 3 tablespoons of the pesto and use your hands to rub the dressing all over the mushrooms. Set aside for 10 minutes.
Heat a griddle pan with the remaining olive oil over a medium/high heat. Add the mushroom wedges to the pan and cook for 2-3 minutes each side until tender and caramelized. You may need to do this in batches. Serve with any remaining pesto.