Add the Greek yogurt, lemon juice, dill, garlic powder, shredded cucumber, salt, and pepper to a small bowl. Mix together, cover, and refrigerate.
Spray a frying pan with cooking spray and add the shallot. Cook for 1 minute.
Add the tomatoes and spinach to the frying pan and cook for 2 minutes.
Pour the eggs into the frying pan and season with salt and pepper. Use a rubber spatula to move the eggs around. When they're almost cooked add in the feta cheese.
Pour the egg mixture into a bowl and top with a tablespoon of tzatziki sauce.