To make the red wine garlic vinaigrette, whisk together red wine vinegar, olive oil, Dijon, garlic, oregano, and 1 1/2 tablespoons water; season with salt and pepper, to taste.
Preheat oven to 425 degrees F.
Cook couscous according to package instructions; set aside.
Place eggplant and zucchini in a single layer onto the prepared baking sheet. Add olive oil and garlic; season with salt and pepper, to taste. Gently toss to combine.
Place into oven and bake for 12-15 minutes, or until tender.
Divide couscous into bowls. Top with eggplant, zucchini, cucumbers, red peppers, olives and feta.
Serve immediately with red wine garlic vinaigrette, garnished with parsley, if desired.