Melt butter in a large skillet. Sauté green pepper for 3 minutes. Pour eggs into skillet and cook, lifting from bottom, allowing uncooked portion to flow underneath. When omelet is almost set, sprinkle evenly with chives, shredded cheese, tomatoes, and coriander. Cover and cook just until cheese melts. Remove from stove and mound sour cream in center. Sprinkle with bacon, salt, and pepper to taste.