Place potatoes in large saucepan. Add chicken broth. Bring to boil. Reduce heat to medium and simmer, partially covered, until potatoes are just tender, about 6 minutes. Drain potatoes, reserving broth. Place potatoes in large bowl. Return broth to same saucepan and boil until reduced to 1/3 cup, about 13 minutes. Pour over potatoes and toss gently until broth is absorbed. Melt butter in medium nonstick skillet over medium heat. Add prosciutto and sauté until crisp, about 6 minutes. Transfer prosciutto and butter from skillet to bowl with potatoes. Add celery, onion, and chives to potatoes. Whisk 1 tablespoon truffle oil and lemon juice in small bowl to blend. Drizzle over potato mixture; toss to coat. Season salad to taste with salt, pepper, and additional truffle oil, if desired. Serve warm or at room temperature. (Can be made 2 hours ahead. Let stand at room temperature.)