Preheat the oven to 200°C. Place the onion, asparagus and courgettes in a large bowl. Add the olive oil, marjoram, sea salt and pepper and toss to combine. Place into a large roasting dish and cook in the preheated oven for 20 minutes, until the vegetables are tender. Turn occasionally. Meanwhile, heat the extra olive oil in a small frying pan over medium heat. Add the chorizo and cook for 3 to 4 minutes or until it is crispy and golden. Place the cooked vegetables onto a serving platter. Top with the crispy chorizo, pine nuts, lemon zest and extra marjoram.