Couscous with Roasted Vegetables

1 ½ cup couscous

2 cup vegetable broth

4 tbsp olive oil, divided

1 lb eggplant, cut into 1-inch cubes

2 zucchini, cut into 1/2-inch rounds or half-moons

1 red bell pepper, seeded and cut into 1-inch pieces

1 red onion, cut into wedges

1 cup cherry tomatoes

3 clove garlic, minced

1 lemon, zested and juiced

½ bunch fresh parsley, coarsely chopped

4 oz feta cheese, crumbled

2 tbsp pine nuts

1 tsp ground cumin

1 tsp smoked paprika

1 tsp kosher salt

½ tsp black pepper

¼ tsp red pepper flakes, optional

¼ tsp salt for boiling