Preheat oven to 400°F/200°C.

Spread the eggplant slices onto a large baking sheet. Sprinkle evenly with 1 teaspoon salt and leave for 15 minutes to draw out excess liquid. Pat the slices dry.

To a small bowl combine the 1/2 teaspoon salt, pepper, chili powder, coriander and cumin. Set aside.

Dry the eggplant. Add the onions and garlic to the baking sheet with the eggplant in an even layer. Drizzle the vegetables with the olive oil. Sprinkle the spice mixture evenly over the vegetables, reserving a small sprinkle for later when you add the tomatoes. Mix well using your hands. Roast in the oven for 25 minutes.

Drizzle the tomatoes with oil and remaining spice mix and add to the eggplant on the baking sheet.. Continue to roast for 10 minutes longer, just until the tomatoes soften. Remove from the oven and allow to cool slightly.

Add all the vegetables to a food processor or blender and pulse until almost smooth but still slightly chunky.

Serve with baked pita chips, crackers or toasted bread.