Beat egg whites (at room temperature) until stiff but not dry; set aside. Beat egg yolks in a medium mixing bowl until thick and lemon colored. Stir 1/2 cup sour cream and salt into yolks; fold whites into yolk mixture.
Melt butter in an ovenproof 10-inch omelet pan or heavy skillet; rotate pan to coat bottom. Pour in egg mixture all at once; gently smooth surface. Cook over low heat 20 minutes or until puffy and lightly browned on bottom, gently lifting omelet to judge color. Transfer pan to oven, and bake at 350° for 5 minutes or until a knife inserted in center comes out clean.
Slide omelet onto a warm serving plate; cut into wedges. Top with remaining sour cream and strawberries, and serve.