Preheat the oven to 400 degrees Fahrenheit.
Slice the cabbage into 8 thick wedges – about 1/2 inch thick. Peel and slice the onion into 8 even wedges. Arrange the cabbage and onion tightly into a shallow oven tray or sheet pan. Drizzle with the lemon juice and a tablespoon of olive oil. Season with salt and pepper to taste.
To prepare the pesto, add the basil, garlic, sun dried tomatoes, lemon zest, pine nuts and 1 tablespoon of Parmesan to a food processor. Blend to form a chunky paste.
Add the remaining olive oil, season to taste and blend again to form a pesto sauce.
Drizzle two tablespoons of the pesto over the cabbage and onion wedges, using your hands to rub the dressing into the vegetables.
Scatter over the remaining Parmesan.
Transfer to the oven to bake for 20-22 minutes until the vegetables are tender and slightly caramelized.