Place 1/4 avocado cut into 3 wedges over the tomato. Set aside.
Crack one egg into a small cup.
Place about 1-2 inches of water in a small sauce pan and bring to a boil.
Lower to a very low simmer.
Add salt and vinegar.
With the handle of a wooden spoon, stir water to create a whirlpool effect.
Drop egg into the center.
Allow to cook 3 minutes.
Remove with a slotted spoon when you see the whites of egg are set. Set aside.
Proceed with the second egg.
Using the same saucepan with water at a low simmer, place a stainless steel bowl larger than the sauce pan to sit on rim of pan but not touch boiling water.
Whisk yolks in bowl until mixture looks about doubled in volume.
Drizzle in butter and continue to whisk until combined.
Stir in yogurt and lemon juice and heat through.
Add salt then taste as adjust.
Top with freshly ground pepper and hot sauce if desired.