Heat 1 tablespoon of olive oil in a large nonstick skillet over medium-high. Add zucchini and saute until it is spotty brown, about 3-4 minutes. Add corn and continue to cook until vegetables are just tender, about 2-3 more minutes. Add garlic and cook until fragrant, about 30 seconds more. Set aside to cool slightly.
Meanwhile, whisk white balsamic vinegar, remaining tablespoon of olive oil and the lemon juice together in a small bowl. Season with salt and pepper.
Toss barley and zucchini mixture together in a large serving bowl. Gently fold in tomatoes, olives, basil and vinaigrette until everything is just combined. Season to taste with salt and pepper and garnish with additional basil if desired. Serve warm or at room temperature.
