Preheat oven to 325ºF. In a small mixer bowl, beat eggs, sour cream and salt on medium speed until well blended, about 1 minute. Stir in tomato, onion and cheese. Pour into buttered 8 inch pie pan, or an 8 inch ovenproof skillet. Bake uncovered until omelet is set and the top is golden brown, 35 to 40 minutes. Makes 2 servings,