With a fork beat eggs. Stir in cheese, sage, salt, and pepper.
In a medium nonstick ovenproof skillet, heat oil over medium heat. Add scallions, reserving 1 tablespoon of the green portion. Cook, stirring occasionally until limp, about 2 minutes. Add eggs. Reduce heat to medium-low, and cook, drawing eggs away from side of the pan with a wooden spoon so that the uncooked eggs run to sides and cook, for 3 minutes. Spread tomatoes evenly over top and continue to cook until eggs start to set and thicken but surface is still runny, 2 to 3 minutes more. Sprinkle with reserved tablespoon scallion.
Place under broiler until top is set and golden brown, 1 to 1 1/2 minutes. Remove from broiler. Serve from pan, or carefully slide onto a serving platter.
courtesay Martha Stewart Living Omnimedia, Inc. All Rights Reserved. 2003