1. Place mushrooms in a bowl, and cover with boiling water. Cover and let stand 20 minutes or until tender. Drain well; coarsely chop.
2. Melt butter in a large nonstick skillet over medium-high heat. Add shallots; sauté 1 minute. Add mushrooms; sauté 2 minutes. Add broth and juice; cook 2 minutes. Remove from heat; stir in sour cream. Stir in 1 teaspoon chives, 1 teaspoon tarragon, 1/8 teaspoon salt, and 1/8 teaspoon pepper. Place mushroom sauce in a small bowl; cover and keep warm. Wipe pan clean with a paper towel.
3. Heat pan over medium heat, and coat with cooking spray. Whisk together remaining 1 teaspoon chives, 1 teaspoon tarragon, 1/8 teaspoon salt, 1/8 teaspoon black pepper, eggs, and egg whites. Pour egg mixture into pan. Cook for 4 minutes or until soft-scrambled, stirring frequently.
4. Place 2 muffin halves, cut sides up, on each of 4 plates. Top each serving with about 3 tablespoons sauce and 1/4 cup eggs.