SERVES 4-6
Preheat oven to 450 degrees. Combine green beans, red onion, and garlic in a shallow roasting pan. Drizzle with olive oil. Sprinkle with salt and pepper. Toss mixture until beans are evenly coated. Spread into a single layer in roasting pan.
Roast for 8 minutes. Add zucchini and roast for 5 to 7 minutes more or until vegetables are tender and slightly browned.
Meanwhile, bring balsamic vinegar to a boil in a small saucepan. Reduce heat and boil gently until vinegar is reduced by half and slightly thickens.
Drizzle vinegar over roasted vegetables and toss until vegetables are evenly coated.