Preparation Preheat broiler. Brush eggplant with olive oil. Sprinkle with salt and pepper. Broil until brown and just cooked through, about 2 minutes per side. Transfer to paper towels and drain. Preheat oven to 425°F. Combine onions and potatoes on large baking sheet. Drizzle with 3 tablespoons oil; toss to coat. Season with salt and pepper. Place peppers on medium baking sheet. Add 1 tablespoon oil; toss to coat. Season with salt and pepper. Roast vegetables until tender and light golden, stirring occasionally, about 35 minutes for peppers and about 1 hour for potatoes and onions. Transfer to large bowl. Place zucchini on medium baking sheet. Add 1 tablespoon oil; toss to coat. Season with salt and pepper. Bake until crisp-tender, about 20 minutes. Transfer to bowl with vegetables. Cut eggplant into 1-inch squares and add to vegetables in bowl. Combine mustard and vinegar in small bowl. Gradually mix in remaining 4 tablespoons olive oil. Add basil. Add dressing to salad and mix to coat. (Can be made 1 day ahead. Cover; chill. Bring to room temperature before continuing.) Mix radicchio, arugula and cheese into salad. Season with salt and pepper.
Preparation Preheat broiler. Brush eggplant with olive oil. Sprinkle with salt and pepper. Broil until brown and just cooked through, about 2 minutes per side. Transfer to paper towels and drain. Preheat oven to 425°F. Combine onions and potatoes on large baking sheet. Drizzle with 3 tablespoons oil; toss to coat. Season with salt and pepper. Place peppers on medium baking sheet. Add 1 tablespoon oil; toss to coat. Season with salt and pepper. Roast vegetables until tender and light golden, stirring occasionally, about 35 minutes for peppers and about 1 hour for potatoes and onions. Transfer to large bowl. Place zucchini on medium baking sheet. Add 1 tablespoon oil; toss to coat. Season with salt and pepper. Bake until crisp-tender, about 20 minutes. Transfer to bowl with vegetables. Cut eggplant into 1-inch squares and add to vegetables in bowl. Combine mustard and vinegar in small bowl. Gradually mix in remaining 4 tablespoons olive oil. Add basil. Add dressing to salad and mix to coat. (Can be made 1 day ahead. Cover; chill. Bring to room temperature before continuing.) Mix radicchio, arugula and cheese into salad. Season with salt and pepper.