Preheat the oven to 425 degrees. Toss the eggplant cubes with 2 tablespoons olive oil, cumin, coriander, salt, and pepper on a baking sheet. Roast for 20 to 25 minutes until the edges turn golden and the cubes are tender but still hold their shape.
While the eggplant roasts, bring the water to a boil in a saucepan. Add the pearl couscous, reduce to a simmer, cover, and cook for 8 to 10 minutes until the liquid is absorbed. Fluff with a fork and let cool slightly.
In a large bowl, whisk together the lemon juice and remaining 1 tablespoon olive oil. Add the cooked couscous and stir to coat evenly.
Fold in the roasted eggplant, parsley, and mint. Top with pomegranate seeds and toasted pistachios just before serving.