Pesto: Place the walnuts, parmesan, garlic, basil, lemon zest and juice of 1 lemonĀ in a blender. Blend until smooth. Add remaining lemon juice and water only if needed for taste/ consistency.
Thinly slice the tomatoes and mozzarella.
Slice the eggplant into 1/2 inch rounds. Brush or spray eggplant w/ olive oil, S&P. Grill eggplant ~5min/ side.
Layer eggplant, mozzarella, tomato & pesto.