Preheat oven to 400*. Place sweet potatoes in a greased 15x10x1-in. baking pan. Drizzle with 2 tablespoons oil and sprinkle with 1/4 teaspoons slat and the pepper; toss to coat. Roast 30 minutes, stirring occasionally.
Sprinkle prosciutto over sweet potatoes; roast 10-15 minutes longer or until potatoes are tender and prosciutto is crisp. Transfer to a large bowl; cool slightly.
Add radishes, pecans, red pepper and half of the green onions. In a small bowl, whisk lemon juice, honey and remaining oil and salt until blended. Drizzle over salad; toss to combine. Sprinkle with remaining green onion.