1.Preheat oven to moderate, 180°C (160°C fan-forced). Generously grease two 10 x 20cm loaf pans.
2.Press two squares of pastry into loaf pans, trimming pastry to 5cm from the base; chill 30 minutes.
3.Line pastry with baking paper; fill with baking weights or dried beans or rice. Blind-bake about 20 minutes, or until golden brown.
4.Heat 1 tablespoon olive oil in a large non-stick frying pan. Add onions and garlic; cook, stirring occasionally, until onions are soft and browned lightly. Remove from heat and transfer to a large bowl.
5.Add a further 1/3 cup (80ml) of oil to pan; cook eggplant, stirring continuously, until browned and tender.
6.Remove from heat and add eggplant to onion mixture. Add remaining oil to pan; cook zucchini and tomato 5 minutes. Stir through tomato paste; cook a further 2 minutes.
7.Fold tomato mixture through onion mixture in bowl. Gently fold in basil leaves. Season with salt and freshly ground black pepper.
8.Carefully turn cool tart cases out of loaf pans and place on a baking tray. Spoon ratatouille into tart cases; return to oven 15 minutes.
9.To make currant gremolata, heat a small frying pan over medium heat. Add pine nuts and currants; gently cook , stirring occasionally, until pine nuts are lightly toasted. Place mixture in a small bowl and, when cool, add lemon zest and parsley.
10.Serve tarts with currant gremolata.