heat olive oil in a lg. cast-iron skillet. add onion and cook 2 min. add potatoes, zucchini, and broccoli. cook, stirring frequently, until vegetables are tender. add 1/2 tsp. salt & pepper.

beat eggs in a bowl. add remaining salt & pepper. pour eggs over vegetables and toss. cook 5 min. over med-high heat without stirring. sprinkle with cheese and cover. cook until cheese is melted and eggs are completely set.