Place eggplant in a non-reactive bowl. Sprinkle with salt and stir well. Let stand for 2 hours. Drain eggplant in a sieve and rinse twice, draining thoroughly; press out excess moisture.

Place eggplant, tomatoes, red pepper, zucchini, onion, garlic, olives, capers, bay leaf, thyme, salt and pepper in a large roasting pan.

Heat vinegar, sugar, and oil in a microwavable container until hot, about 1 minute, stir into vegetables.

Bake in a 350 degree F (18OC) oven for about 1 1/2 hours (1 hour for a convection oven), or until vegetables are softened and liquid has evaporated, stirring every 20 minutes. Remove pan from oven, discard bay leaf and stir in tomato paste.

Remove hot jars from canner and spoon relish into jars to within 1/2 inch (1 cm) of rim (headspace).

Process 15 minutes in a boiling water bath for half-pint (250 mL) jars and 20 minutes for pint (500 mL) jars.