In a medium bowl, whisk together the whole eggs, egg whites, and Greek yogurt until the mixture is smooth and no white streaks remain.
Finely slice the green onions, separating the white and light green parts from the dark green tops.
Place the sourdough slices in a toaster or under a broiler until golden brown and crisp.
Heat the ghee in a non-stick skillet over medium-low heat. Add the white and light green parts of the onions and sauté for 1 minute until fragrant.
Pour the egg mixture into the skillet. Let it sit for 30 seconds, then use a silicone spatula to gently push the eggs from the edges toward the center.
Continue cooking low and slow, folding the eggs gently to create large, soft curds.
When the eggs are nearly set but still look slightly wet, stir in the dark green onion tops, sea salt, and black pepper.
Remove from heat immediately and pile the scrambled eggs onto the toasted sourdough slices.