In a medium bowl, whisk the eggs, yogurt, chives (you can add the chives now or sprinkle on top when serving) and a pinch of salt and pepper.
Heat a medium size non-stick pan over medium-low heat. Add the butter and let it melt.
When the butter is melted and bubbling, pour in the eggs. Allow to cook for about a minute then, using a spatula or wooden spoon, start to scrape the eggs from the edges of the pan to the center, repeat until the eggs are almost cooked, about 3 to 4 minutes.
While the eggs are cooking, toast your bread. Top with sliced or mashed avocados. Divide the scrambled eggs and transfer on top. Top with chopped tomatoes and sprinkle with chives. Serve immediately and enjoy!