To make herb puree, squeeze juice from lemon. Process with herbs, sugar, olive oil and salt and pepper in a small food processor until smooth. Use a dash of water if needed to loosen the consistency.
Bring potatoes and salted water to the boil and cook for 8-10 minutes until tender. Drain well.
Heat oil in same stockpot over a medium to high heat. Return potatoes with white onion bases, chickpeas and curry powder. Cook, stirring occasionally, until hot. Season. Stir in onion tops. Cover to keep warm.
Meanwhile, toss zucchini, capsicum and eggplant with olive oil. Season.
Heat an oiled grill plate or non stick frying pan over a medium to high heat. Add vegetables in batches. Cook for about 3 to 5 minutes, turning occasionally, or until tender.
Serve potatoes and vegetables topped with herb puree.