Heat oil in 12-inch nonstick skillet over medium-high heat until hot. Add potatoes, zucchini, bell pepper, salt, and pepper. Cook and stir 2 minutes. Reduce heat to LOW, cover, and cook 8-10 minutes, stirring occasionally, until vegetables are tender.
In medium bowl, lightly beat eggs with milk and remaining 1/2 teaspoon seasoned salt. Pour over vegetables. Cook over low heat, covered, 10 minutes, or until eggs are nearly set.
Heat broiler. If skillet has plastic handle, wrap with foil before placing in oven. Broil frittata 2 minutes or until top is set and browned. Sprinkle with New York Sharp Cheddar cheese; broil 1 minute longer until cheese is melted. Cut into wedges to serve.