This is a great dish to serve for summer get-togethers. It's filled with crisp veggies fresh herbs, it's easy to prepare and it can be made ahead. Serve it warm or at room temperature.
Heat the broiler. Combine 1 gallon water and 1 tablespoon salt in a pot and bring to a boil.2.
Meanwhile, cut the zucchini into roughly 1-inch pieces, then combine with the eggplant, chopped onion, 1/4 cup olive oil and remaining 1 tablespoon salt. Spread in an even layer on a rimmed baking sheet and roast for 10-15 minutes, stirring them every 5 minutes or so, until they are evenly golden and tender.3.
When the water comes to a boil, add the couscous and cook for about 6 minutes, until it's tender and still has a little bite. Drain it and set aside.4.
Strip the leaves from the thyme and finely chop them with the parsley. Warm the remaining 1/4 cup olive oil in a large skillet over medium heat, then add the garlic and herbs. Cook for just 30 seconds to 1 minute, before the garlic has a chance to brown.5.
Stir in the tomato paste and continue to cook, breaking it up with your spoon, for 5-10 minutes, until it's fragrant and deeply caramelized. Remove the skillet from the heat and fold in the roasted vegetables, couscous and remaining 1/2 cup water, followed by the olives and basil. Serve warm; leftovers keep well for a few days.