1.In small bowl, whisk yeast, sugar and the water together. Cover; stand in warm place about 10 minutes or until mixture is frothy.
2.In a large bowl, add flour, salt and pepper and stir in yeast mixture and oil; mix to a firm dough. Turn dough onto floured surface; knead about 10 minutes or until smooth and elastic. Place dough in large oiled bowl. Cover; stand in warm place about 30 minutes or until doubled in size.
3.Place eggplant in strainer. Sprinkle with salt; stand 30 minutes. Rinse eggplant under cold running water; drain on absorbent paper. Heat oil in large frying pan; cook onion and garlic, stirring, until onion is soft. Add eggplant, capsicum, zucchini and celery; cook, stirring, about 5 minutes or until vegetables are soft. Add paste and stock. Cook, stirring, until mixture thickens; cool.
4.Transfer dough to floured surface; knead until smooth. Divide dough into four pieces; roll each piece to a 24cm round. Spread one half of each round with a quarter of the vegetable filling; top with a quarter of the cheese. Fold plain dough over cheese to enclose filling; press edges together.
5.Place calzone on oiled oven trays; brush with a little extra oil. Cut two small slits on top of each calzone; bake, uncovered, in hot oven about 20 minutes or until browned.