Heat oven 190°C (conventional).
Place onions and cherry tomatoes on a lined baking tray and coat lightly with olive oil. Sprinkle tomatoes with sumac.
Roast in the oven for 20 minutes or until onions begin to caramelise and the tomato skins are soft and beginning to wrinkle. Set aside.
Slice eggplant and zucchini into 1cm circles. Mix olive oil with Garlic Lovers’ Spice and brush over the vegetables. Season to taste and cook on a griddle pan until soft.