1. Drop the asparagus, peas, green beans, fava beans, and carrots into a large pot of boiling salted water and cook for about 2 minutes, or until the vegetables are tender but still crisp. Drain the vegetables and immediately plunge them into a large bowl of ice water to stop the cooking process.
2. In a small skillet, sauté the pearl onions with 3 tablespoons of water and 3 tablespoons of sugar until caramelized.
3. In a large skillet, melt the butter in the oil over medium-high heat. Drain the vegetables and transfer them to the pan. Add the caramelized onions and sauté the vegetables until heated through. Season with salt and pepper to taste.